Try this http://mrtweet.net -- subscribe to their service and once a month, you will get a direct mail tweet that gives you a link to a full report about your activity, which followers you aren't following and suggestions on people that could appeal to you. I really like that they give you statistics about the people they suggest - like whether they follow people, if they communicate and maybe most important - the average number of tweets they send per day.
You should check it out and see if it will help you :)
This is my monthly update to show you a sample -
Engaging in Conversation 79% of the time
Posting 19% Links
When you try it out - let me know what you think :)