TrueMusic is a pure Java music player that supports MP3, Ogg Vorbis, Ogg FLAC, Native FLAC, Speex, WAV, AU, AIFF, SND, and MIDI. It will attempt to match the native look and feel. It requires Java 6 or later.
PlayaPlaya is a "fire-and-forget" audiobook player that stays out of your way and just works. Logout, and it'll save your place. Launch PlayaPlaya again, and it'll resume where you left off. Launch it with different playlists, and it'll track each one separately.