Ali: I didn't have time to get to this before, but there are a few tools that I have found to be especially useful in tracking interaction on Twitter. Crowdbooster (http://crowdbooster.com/) Is really handy: it calculates all of your Twitter interactions for you, measures impact, and makes recommendations to help you amplify reach.

Also, I don't know if you use Hootsuite, but you can pay $10 a month to archive up to 10,000 messages: you select a column, so, say, your "My Tweets, Retweeted" column, and you can save them and download them to a spreadsheet at your leisure. It can be a real time saver.

Hope that's helpful!