I installed Twitbin as an add on for FireFox. So far I don’t like it very much, the refreshing is really slow even though you can set the refresh rate to be faster. However setting it to be faster doesn’t do much of anything. I do like being able to see the twits on the side of my browser, that is pretty decent, however if you want to respond to a particular person you have to go to the full on twitter page to do so.
Try it out for yourself. Go to http://twitbin.com/