If you’re a web chat user on OS X, you might want to take a peek at the just-released Gabtastik. What you’ll find is a WebKit based application that functions as a site-specific browser across three different online chats: Facebook Chat, Google Talk, and meebo. The Gabtastic menu lets you switch quickly from one to another, and by using the application you don’t have to remember which browser tab you were chatting in.
You could build most of the same functionality yourself (everything except the switching) with a general-purpose site-specific browser such as Prism, Fluid, or Hana. But with this free download being just a click away, you might as well not bother to build your own.