Twitter lists can help clean up your feed, but creating lists is a painful job right now, where you have to individually search for and add users. TweetBe.at simplifies the process with powerful list management tools.
Connect TweetBe.at to your Twitter account and you will have plenty of ways to filter users. Options include those you follow, those who follow you, those who are near, those who mentioned you, and much more. Then you can further sort that list based on people who have more than a certain number of followers, those with a high Klout score, or which Twitter client they use.
I tried it out with three different Twitter accounts and found that the filtering worked just as advertised and actually helps you get a better idea of the kind of people you can sort into a list. For example, I created a list of people with whom I interact on Twitter (by how often they mention me), but who don't tweet regularly (sorting by days since last tweet).
Tweetbe.at is a cool tool and it's completely free, so give it a whirl.