I've already suggested this or something very close to it in this thread. My idea actually leaves it open to multiple selections from a user defined menu, but the idea is still the same. You could use it for "marking" tracks to appear in special playlists including favorites but not limited to just that. "F" may be for favorites, but "C" may be for cruizing tunes, and "S" might be for tunes that get you pumped-up before going snowboarding. You guys get the picture, while your listening, it would be very convienient to mark a song with a special code, easily altered/changed at a later time without trying to remember why you marked it in the first place. This would also be helpful for giving "marked" tags to songs for other reasons (re-rip, has pops, duplicate on player, etc...). Basically a totally flexible way to mark tracks instead of just marked or not marked.