I happened to accidentally stumble upon this social media app called ThinkUp a few months back. You run it on your own server and it ties in to accounts on facebook, twitter, and google+. Then, it sucks down your posts and starts doing a lot of analysis and trending with pretty graphs and such.
The best was to get a sense of how ThinkUp works is to go play with my instance.
There are a lot of fun features like the ability to save your conversations and embed them in other pages on the internet. Here's an example:
The fundamentally cool thing about ThinkUp is it allows you to keep control of your data. All your tweets are stored in a mysql database for all eternity. No more fumbling around trying to seach your old tweets: they're all right there.
I suppose most people probably don't care about these sorts of metrics too much but if you are a dedicated twitter user you should definitely install it and take control of your data.
Oh, and don't worry, this stuff is all open source.