This is not meant to be an open discussion on how to improve favorites, but rather a specific feature request that I'd like feedback on.
I would love to see a feature added that would let users arbitrarily create "groups" of favorites, and drag individual favorited questions under these groups. I have about 2 pages of favorites (I know others have much more), and finding an individual one is quite difficult, especially since the specific question title is usually forgotten. I just added this question to my favorites, since I liked Andrew Whitaker's answer, and might want to come back and look at it later; I'd love to add this to a group called, say, "Useful Code".
I've favorited other posts since they had neat tricks in them, or because there were answers written on interesting theoretical computer science topics. Having different groups for all these areas would be immensely helpful in finding posts later.