This is what MP3.com looked like just moments before it went offline at 12:00 Pacific Time.(roll your mouse over to see what it looks like now)

I have put together a list of other sites that you can visit to listen to mp3s or if you are an artist, put UP your MP3s.

If you can host your own MP3s on your own site, you can have Ismp3.com list them in their directory.
By the way, you can do this with Collected Sounds too. I do not have a directory up yet, but if you have a spotlight or CD review (or want one) I can link to MP3s from that page.

1Sound.com
ACIDPlanet.com
ArtistGigs.com
Artist Launch
BeSonic.com
Clear Channel New Music Network ...if you're not against them...
dmusic.com
Emnergent Music.com
funender.com
garageband.com
GetMeMusic.com
IC-MusicMedia.com
IUMA.com
mPulse.com
MP3nut
NowhereRadio.com
PYBand.com
SongRamp.com
SoundClick.com
Vitaminic.com