I've created a couple of lists that I use to filter my tweets and make it easier for me to read. The problem is that I still want to read my unfiltered "main" feed but minus all the tweets that I've already read in the lists. Otherwise, I have to deal with massive duplication of information.
(also, I have a Formula 1 list that I like, but during race weekends, I want to avoid spoilers as I watch the races on Tivo and am always a couple days behind)