Hmm...plenty of good US stuff out there, too much to mention!
For me, it's mainly about French/UK stuff these days - loads of quality stuff on UVPR but there's also some great US stuff, try the following bands:
Crown Court (brickwall Oi! from London)
No Time (Brutal Oi! from Pittsburgh)
Rixe (Fantastic French Oi!)
Dwarves (Still going, still rocking and still offensive!)
Janitors (77 style punk/Oi! from France)
Hub City Stompers - (Amazing Street Ska from the US)
I'll think of more but it's been a long week!
Oh wait, Masked Intruder - pop punk with bubblegum vocals but all their lyrics are about getting arrested/breaking the law/getting rejected.