For many early iPhone users, this was Google Maps and the way it made use of the touch screen. For G1 owners and other early Android adopters, it may have been the barcode scanner. And for today’s Android-loving masses, it’s Google’s turn-by-turn navigation.

Google is scheduled to launch the Android marketplace on Google TV devices in early 2011, which will potentially add a lot of new functionality to existing and future Google TV devices. So what will be Google TV’s killer app? Here are three possible candidates:

Shazam

London-based Shazam has been offering mobile phone applications to identify music for close to a decade now. The idea is simple: Want to know the title of a song you’re hearing? Just take out your phone, fire up Shazam, record a few seconds, and immediately have your handset tell you song title, band name and other details, complete with a link to buy the song online. The company has been hugely successful with this and passed the mark of one billion identified songs in May.

Of course, chances are, you’re hearing the song on TV. So why would you even deal with your cell phone, instead of simply pressing the Shazam button on your remote control?

Shazam uses acoustic fingerprinting to identify the songs you hear, but this type of technology isn’t limited to music recognition. The company has already been striking collaborations with TV networks like Syfy and HBO to get viewers to engage with content. Most recently, viewers were able to unlock special content for Syfy’s shows Eureka and Warehouse 13.

One could imagine a ton of other use cases for acoustic fingerprinting of TV content, many of which have to do with advertising. Why not measure the shows as well as ads a viewers is watching across all networks and content sources with the help of Shazam, and then personalize their ad experience based on these viewing patterns?

Karaoke

I have to credit none other than Google TV Product lead Rishi Chandra for this idea. Asked how the killer app for Google TV will look like, he told me during an interview in October that he sees a lot of potential for “social experiences that you have in the living room, things that you want to share with other people.” He added: “Why couldn’t karaoke be a great application?” Check out the full interview for more:

I really like this idea, despite not being that much into karaoke myself. There’s something very compelling about the idea that a device like Google TV doesn’t just play video you’d passively watch, be it from the web or your cable company. Instead, there will be applications that will allow you to create, manipulate and mash up content. Karaoke is just one example — one could also imagine video remixes, simple collaborative video editing tools or even game shows shows like Who Wants to Be a Millionaire? extending the experience into the living room with the help of special apps.

Mystery Science Theater

The power of meta-data still remains largely untapped in the world of online video. Google TV has a unique opening in this space because it’s able to engage with both online and cable content. Imagine you’re watching an episode of The Simpsons, complete with a collaboratively edited subtitle that explains all the pop-cultural and Simpsons-specific references. Or imagine if a running commentary of hardcore fans had been available to make some sense of those final Lost episodes.

Google TV wouldn’t be the first platform to offer this types of metadata-based commentary: The folks at Joost and others tried to get something like this off the ground before. But there has until now been a sort of chicken-and-egg problem, in that you need a lot of content to make this type of commentary valuable to end users, but no one will add content if there’s no audience for it.

Luckily, Google wouldn’t have to reinvent the wheel: Remember Google Wave and the way one could play back waves to catch up on discussions? Now imagine you catch up on an episode of Glee recorded on your DVR, and Google TV plays back all of Glee-related tweets your friends sent out when the episode originally aired, precisely times so that each and every tweet relates to the scene you’re currently watching. It’s like your very own Mystery Science Theater.

Got your own idea for a Google TV killer app? Feel free to share it in the comments.

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TV apps may not be big business just yet, but they’re hardly revolutionary. So why did Intel CEO Paul Otellini tell analysts last week that this is going to be the “the biggest single change in television since it went (color)?” We decided to dig a little, and found an interesting patent application for a “network media player with user-generated playback control” that Sony applied for late last year. Here’s the gist of it:

The patent application essentially describes a network media player able to generate and consume XML-based metadata for programming from any source, including over-the-top, local media and cable TV. This type of metadata would then be stored on a central server and exchanged between users through social networks, or made available by broadcasters or other entities.

Users could also vote on metadata and freely mix video from different sources. From the application:

“(A) user may create a Cliff note version of the recent Super Bowl game footage to tailor such footage… For example, one user may tailor the footage so that only the “snaps” for the entire game are included within the Cliff note version. In this way, the user can view the entire series of plays within the game without all the extraneous material unrelated to such plays. Thereafter, other users can access this version or Cliff note of the media and amend it to their needs or desires.”

Users could even cooperate on metadata to assemble a collection of the best moments of an awards show, and there could even be a function to add graphical overlays. Again, from the patent filing:

“User-generated overlays can be used to create custom playback of content. For example, a user could overlay a frame image, add a ticket bar, place a logo in the corner of the screen, add a sound track, or perform any other overlay function.”

Essentially, you could think of this type of metadata as something like KML for your TV. Owners of such a network media player could annotate and showcase media in very much the same way Google Earth users can generate and submit their own KLM files to annotate existing maps. Google could profit from it by learning a lot about the device’s user base, and advertisers could deliver custom-tailored ads through simple XML feeds.

How likely is it that we’re going to see such a system on display at Google I/O this Wednesday? Unfortunately, not very. The patent application was filed by Sony Computer Entertainment America (SCEA), which is overseeing the development of the Playstation, but is not in charge of TV-related products. Then again, TV and gaming are growing together, and it would certainly be a smart move by Sony to utilize its SCEA assets for any over-the-top product.

However, the bigger lesson is that the thing that will make Sony’s “Smart TV” products unique isn’t simply a TV-optimized version of Android with yet another Twitter client, but custom-tailored apps made to impress users and give the platform an advantage over competitors like Vudu, Boxee or Yahoo Widgets.

That’s not an entirely unprecedented strategy. Google has invested a lot of resources into giving Android phone users exclusive apps like Google Maps with free turn-by-turn directions, and device makers like Motorola have customized Android to make their phones stand apart as well. So if “Smart TV” truly wants to be revolutionary, it better offer us some apps that we haven’t seen anywhere else and that greatly enhance the functionality of the device — like, for example, a cool metadata mashup.

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Coincident.tv’s CEO David Kaiser called the Glee trailer “very short and modest” when I talked to him on the phone late last week. However, the technology under the hood is pretty interesting, and it could be used to one day not only enrich video on the web and various devices, but actually to add another dimension to transmedia storytelling and make the experience of watching shows like Lost or Flash Forward much more immersive.

Coincident.tv has essentially developed an XML-based metadata framework dubbed Cue Point Language that makes it possible to add additional content, links or even various types of actions to any predefined point of a video. Cue Point Language is meant to be platform-agnostic, so one could imagine using this within a PC-based web browser, on a set-top box or even a mobile device.

At this point, the company is concentrating on Flash, but it has already done some proof-of-concept implementations in HTML5 as well, and it has ported its player to Android devices. Cue points are saved in a file separate from the video data, and adding them to clips can be done with an editor that Kaiser described as similar to Premiere or Final Cut, or with the help of a Perl library.

So how does all of this look in practice? Kaiser gave me a demo of various implementations that the company has been using to pitch its technology to Hollywood and beyond, and one example that he said went really well with the studio crowd was an application that enhances episodes of a TV show with additional material — for example, documentary clips explaining the fashion or the politics of the time in which a show is set. “It’s very much a DVD-like experience,” Kaiser explained, with the obvious difference being that DVD extras are static content, whereas this solution not only makes it possible to dynamically add new content, but actually to also add new episodes of the show as the season progresses. Think of it as a desktop application that offers you a season pass to a show, complete with added extras.

Another reason Coincident.tv that could be very compelling to Hollywood is its ability to add text messaging and robo-call features to online content. Kaiser demoed a clip that featured a character sending a text message, and seconds later a message appeared on my phone. The same could be done with a robo-call. I know, sounds annoying at first, but think for a second about the possibilities.

What if a show like Flash Forward that features a very complex storyline, with lots of clues along the way, called some of its most hardcore fans just as they’re watching the scene of a main character receiving a phone call, only to give them the exclusive chance to hear the other side of the conversation that is not featured in the video itself? Calling people while the show is on TV doesn’t make sense in the age of Hulu and Tivo, but cue point-based actions could help to break down the fourth wall and possibly even enhance Alternate Reality Games like the ones previously built around shows like Lost and Heroes.

Kaiser also told me that he sees a lot of potential in enriching educational and corporate videos, but it looks like Hollywood will be first to embrace Coincident.tv. The company is scheduled to announce further partnerships later this month.

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