In an effort to reduce the number of 'always open' tabs that I have in Firefox I have been looking for a desktop Twitter client. The two most popular Ubuntu (and other Linux system) solutions are gTwitter and Twitux.
At present gTwitter is still in beta, and has the advantage of being able to read others' updates and update your own from one window. However you can only see the full text for one message at a time. This isn't a major problem, but isn't the interface I prefer.
Twitux annoyingly requires you to update Twitter from a second window, but I still prefer it. I can see the full text of all updates at once, and the graphics seem to be that little bit cleaner.