Rise Against!!! They send some amazing messages and make your ears orgasm. After that is The Misfits! I love their brutality. It's just so cruel, and beautiful :)
It always changes, but as of lately, it's been constant Comeback Kid while I'm driving. Before that it was Rancid, occasionally I'll throw in some Gun Club, Swingin' Utters, Youth Brigade, Screeching Weasel, etc. I wish I would have realized at 16 that Black Flag wouldn't be my favorite band for the rest of my life, because I probably wouldn't have gotten the tattoo.