I think one kind of player that is missing in Maemo world is simple, no nonsense directory based player that doesn't try to be annoyingly smart and just plays all files in a directory sorted by file name (or provides effective way to create playlists based on what's already organized in the file system). Another area to concentrate on is proper support of various formats (like ogg and flac) and also on important but always neglected things like gapless playback. Maybe it's just me, but any new development effort that doesn't address these issues in any way is just pointless.