Recently, one of my colleagues was talking about the idea of rolling out an internal version of Twitter, and that lead me to some recent exploration into Yammer, a closed "enterprise" tool with some Twitter-like functionality. While doing a bit of experiment with it, I came across a feature that I've heard about with Twitter, but been unable to figure out how to take advantage of -- specifically following hashmark tags.
While researching that, I came across another Twitter client, TweetDeck, that makes it easier to do things like following tags. Tweetdeck features a handy multi-column interface that makes it easy to view and manage multiple Twitter accounts at the same time. So far, I'm pretty impressed. While the user interface takes a little bit of time to get used to (very tiny buttons), once you get the hang of it, it seems pretty powerful. It has a lot of cool functionality built in too.
I also loaded the iPhone app -- I love the interface on the iPhone, but I was able to get the app to crash pretty quickly, just by trying to open a link. There were a bunch of comments about the app crashing, so the jury's still out on the best Twitter iPhone app. Tweetdeck is free, so that is one plus!
TweetDeck is definitely worth checking out.