Twitter can be an excellent remedy to boredom on a long bus journey or car journey. But you should make sure you install a decent Twitter client on your phone rather than just relying on Twitter's mobile site.
Gravity is one of the better S60 clients out there. One of the things that makes it stand out from programs such as
The feed view in Gravity is compact and easy to use. All you need to do is click on a tweet and a small toolbar will appear underneath it, allowing you to reply, retweet, DM, etc. Tabs at the top of the timeline allow you to quickly switch between the different views (Timeline, Replies, Friends, Messages, and Favorites).
Gravity is loaded with enough features to keep even the most insatiable of Twitterers happy. You can post pictures to Twitpic, TwitGoo, Posterous, and the like, as well as previewing images from these sites too. The app also has ping.fm support, dark and light themes, Twitter search section with multiple search tabs, and a feature for categorizing your friends into groups.
Gravity is so well designed and its features so useful that it's difficult to find fault with the app. I guess some kind of GPS tagging features or a more customizable interface would be nice to see in the future.
I defy you to find a better Twitter client than Gravity for S60 phones. In fact, it's better than most of the desktop clients I've used, too.