If your ideal evening is installing something, realising it doesn't work very well, trying to reinstall it again then taking it all off and putting the original version back on before eventually getting to bed with very sore eyes at 3.47am, you're well within the target demographic of Rockbox and its custom MP3 player firmware.
Upgrading older iPods (up to fifth-gen, but not the Touch) and numerous models by Creative, Sandisk and the likes of Archos and iRiver, Rockbox 3.0's main boast is adding OGG and FLAC playback support to these common players, also opening up locked devices for easy use as an external HD...
Also, if you're not a particular fan of iTunes, it allows full and easy "drag & drop" music copying to iPods, plus a more standard "big list of stuff" interface instead of all that nonsensical grouping. It's also a bit better at managing and organising playlists on the move. Plus it's skinnable, with the "community" creating and managing a vast selection of homebrewed custom themes to brighten up your little player's screen.
It's dead useful for those not afraid to invalidate warranties, basically.