You can choose whether it starts on login, whether you are given an extra notification when battery resources are at a level you define and can restrict display if designated applications are currently running:

You also have complete control over the information presented in the alerts:

With my Growl configuration, the notifications look like this:

   

It’s a very simple application that does not require a substantial amount of system resources (as shown below). There have been times when I have had the MacBook Pro become unplugged and not noticed the screen dim only to discover much later that I’m on 50% battery left. This utility would have definitely come in handy then and is now a part of my “must have” applications.

I had a bit of trouble trying to send a PayPal donation to the author via the link on the page, but managed to do so via the standard PayPal “Send Money” option. As always, I highly encourage folks to support independent development on the Mac.

If you use Unplugged or have suggestions for other small-but-useful utilities, drop a note in the comments.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• Why iPad 2 Will Lead Consumers Into the Post-PC Era
• The Near-Term Evolution of Social Commerce
• Content Farms: The Players, The Benefits, The Risks