Well, let's see:

1) Rio 500 MP3 player
2) Rio 800 Extreme MP3 player
3) SliMP3 MP3 player
4) Rio Car 10GB
5) Wife's Rio Car 10GB
6) Aiwa CDC-MP3
7) Wife's CDC-MP3
8) iPaq 3650 running familiar Linux and playing MP3s
9) iPaq 3850 running Pocket PC 2002 and playing MP3s
10) Sharp Zaurus SL5000D running Embedix Linux and playing MP3s

...of course, those are just the portable devices. There's also:

11) FreeBSD file server with main RAID 0 MP3 repository, SliMP3 server code, and SAMBA server sharing MP3s to two wireless notebooks and two desktops, which also play MP3s.

We have a few too many gadgets for a 2-person/1 cat household.