If you look strictly for straight forward punk from 1985 to now I would say these:
Authority Zero (Some straight punk songs, some punk songs with a little ska in it). Check out thier first records, A Passage In Time
GBH. Listen to songs like Punk Rock Ambulance and Sick Boy.
Classics Of Love is a pretty new band (2008) playing melodic punk. A EP is coming out in April this year. Their MySpace.
For The Win plays simple punk. A little pop-punk too maybe. MySpace
Black Flag (I prefer the Keith Morris years of the band),
those are some of my favorites.
I would say try looking up some stuff from the Angry Samoans, MDC, DI, and as already mentioned The Circle Jerks!!!
I want to add The Reagan Youth!!!
http://www.youtube.com/watch?v=2uzMva67mEY Here are some early Angry Samoans!!!!!!:cool: