I have this huge set of 5000 songs from SXSW from last five years I want to listen to, but I'm always put off because if I import them into iTunes, they pollute the "artist" namespace, taking my existing 240 artists and adding another 3926 to them. This makes the 'artist' menu on the ipod unusable, which is unfortunate, because it's my primary way of playing music.
What I'd prefer to be able to do is to divide my collection up into disjoint libraries/collections/sets, and to have the portable player device respect that by providing that as a top-level menu, but then providing normal functionality within that. (There are other things I would use this for as well besides SXSW.) But I have no idea what other players are capable of (or whether they're any good.)