I'm always changing. Standard favorites are older Metallica, Pantera, and Sepultura. Master of Puppets, Damage Inc., Four Horsemen, Frayed Ends of Sanity, Dyers Eve, Walk, Fucking Hostile, Becoming, Arise, Refuse Resist, etc. Lately I've been listening to a lot of newer Godsmack (Sully's drumming is bland and lifeless on the first albums), Red, and Stone Sour. Particular songs are Enemy, Breathe Into Me, and Get Inside. There's also Slipknot.
If I just need inspiration in general, I find there's nothing better than Yanni - One Man's Dream or Gary Hoey - Fade To Blue. I'll also throw on some Beethoven or Mozart.
If I'm in a "fuck you" mood, it's Brotha Lynch Hung, Mr. Doctor, Mr. Shadow, or Mac Mall. Specific songs, Rest In Piss, Loc 2 Da Brain, One Nigga Dead, Bloccstyle, You and I Know, Gangsta Stepp'n, and My Opinion.