Several folks have been sending me this tip in so I figured it was about time I got to posting about it. Seems like the original claim to fame, as far as finding this tip goes to the folks at Digital Inspiration.
1. Create a bookmark for this address: talkgadget.google.com/talkgadget/client
2. Right-click on that bookmark and select “Properties”.
3. Check the box that says, “Load this bookmark in sidebar” and you are all set.
Now you can get your Google chat going without launching a client and you can keep it with you at all times because it is right there in your Firefox sidebar.