<< ska = crap >>
and johneetrash = gay
Anyway...
Black Flag
Ramones
Mike Ness
Social Distortion
MxPx
Guttermouth
Descendents
and others, but those are the ones I could name offhand.
Edit: I used to think Offspring was good, but I hate them more with each new album. I saw them just after Smash was released, but before they really became mainstream. Guttermouth opened for them, and after seeing them play Offspring was a letdown. They were OK, but to be outdone by your opening band is just sad. Now Offspring is just a bunch of pantywaist pop prissies.