Currently the excellent MAME information and ROM repository is offline. It would appear that their web hosting company went bust.

Update 08/Dec/2003: For those of you who desperately want back, and can’t figure out how to find ROMs by any other means, you can either hit up Usenet (alt.binaries.emulators.mame) or hookup with a ROM burner in your area. Also other suggested reading is on Usenet. Also this site looks like it could be good for getting individual ROMs.