Another option:

mpd -- (Music Playing Daemon) a music playing daemon; it sits idly in the background until you want something played, then sits busily in the background playing it. No user interface.

Use it in conjunction with one or more of:

mpc -- (Music Player Control) command-line controller; not especially
helpful (mostly).

mmpc -- (Maemo Music Player Control) works quite nicely, interface similar to OS2007 built-in media player.

powerlaunch -- Not sure this is available for OS2008, but alters behavior of hardware keys. Can be used to control mpd with display off and touchscreen input ignored.

(other software) mpd has a network interface, so you could even control it from your desktop machine. Saves fishing it out of your pocket, I guess.

At the moment, I'm mainly using mmpc.