Use this to export your friend or follower list so you can read and manage tweets in any RSS reader like Netvibes, Mail.app, NetNewsWire, etc. It's a quick script, so please let me know if you have any suggestions or trouble with it.
Also, I'd really like to know how you're using the OPML file to help you use Twitter, so please share! With some feedback, I'll hopefully be able to build more useful tools.