TwitterCounter for @legacyb4 While Twitter itself offers very little statistical feedback on their services, there are a variety of sites now tracking tweeting frequency, tweeting patterns, follower growth, etc. on Twitter. Here are just a few:

- twittercounter.com
- tweetrush.com
- tweetstats.com

Additional interesting ones that I've recently found:

- twitter-friends.com
- tweetvalue.com

Lastly, there are some sites now popping up that supplement Twitter's basic feature set with additional functionality:

- futuretweets.com

Feel free to add to the list of other ones that might be of interest!