There is a nice view in Songbird called "Tag cloud". It shows you your genres, artists or albums with the more popular items at larger font sizes and the lesser popular ones at smaller sizes. It's quite a nice way to browse, but crippled by the fact that double clicking on a genre doesnt take you anywhere.
MC could implement this nicely. It would essentially be just another "Library view" but instead of a grid of album art, it would be a list of genres and by double clicking on it you would be taken to the next level (ie. artists).
I'm sure MC could add some more power to it to by letting us customize the rules for deciding "popular". There could be a little drop down menu with a list of tags that we can use to set how the size of items is evaluated. Personally I'd use my [album rating] tag or maybe [number of plays].