Twitter is fantastic but twitter.com? notsomuch. Programs like tweetdeck add the features we desire but if want something entirely browser based,
Brizzly is the Twitter.com replacement you never knew you were looking for.
So what's it do? In short, it vastly improves twitter's web interface - automatic url shortening, picture and video thumbnailing, fixed side columns so you don't have to scroll up for the useful stuff and general improvements across the board.
I've completely replaced twitter.com with it.