On a personal note, I use Twitter lists to organize people I follow. I benefit from this to track tidbits I might otherwise forget, such as people in Memphis (who I have asked for doctor recommendations) and philosophically inclined people (hard to find, but I look for). I also appreciate looking at other people's lists. When someone creates a list that I might appreciate (such as ANOTHER Memphis list or philosophers list), I'm gonna follow their lists.

I think there's a lot of opportunity in the lists. It just depends upon what you want to get out of your Twitter use.