Start with the classics:

Dead Kennedys
The Clash
Bad Brains
Youth Brigade
Black Flag
Subhumans
Minor Threat

Newer stuff to check out:

Millencolin
NOFX
Rancid
Bouncing Souls
Avail

If you're daring you could try:

Grimple
Aus Rotten
Choking Victim
Destroy!


Enjoy!