If there is one thing that Twitter could do better (besides increasing the character limit to 256 — which I think would be better for more “mainstream” users) is better list management. I was planning on spending an hour or two just going through my lists and followers one Saturday just so I can get a bit more out of the service. Using something like TweetBe.at — and the other services listed — might be helpful.
I keep my “following” list pretty low — and I think I should lower it still. I’ve created lists by subject and added people to them so, when I need to, I can easily find relevant content without the cluttering my main feed. Some lists I keep are for NYC/Hoboken emergencies (when Hurricane Sandy hit the area), the New York Yankees and New York Giants, and Apple news.