Make Twitter's web interface sexier with Helvetwitter
Helvetwitter isn't perfect for everyone. One if its big pluses is that it doesn't use the entire area of your browser window, so you can shrink Twitter down and drag it off to the side of your screen. On the other hand, the lack of icons can make it harder to pick out whose tweets you're reading at a glance. The lack of sidebar is both a plus and a minus: I personally don't miss it, but you might if you actually care about trending topics. You can install Helvetwitter in Greasemonkey if you use Firefox, and the site offers instructions on how to set it up on other browsers.