Mudvayne's "LD 50" is cool, the rhythm section actually knows how to play their instruments (the bass player has one of the best tones ever), and their music is a lot more complex than the rest of those mooks (system of a down included), there were some weird time sig changes and fancy playing on songs like "Severed." Their newer albums are crappier though.
I also don't mind Slipknot. They're idiot metal to be sure, but once again, it's nice to hear some guys that SORT OF know how to play their instruments on the radio instead of linkin park and nickelback.
I used to be a big fan of Korn, and I still think they weren't half bad. They spawned a legion of horrible shit, and to be sure plenty of their stuff is terrible, but they were actually pretty damn original and had some cool sounding stuff. Their riffing style really is distinctive and interesting, especially on the first couple of albums.
Hmm...other mainstream hardrock bands of the last 10-15 years that I like or liked...Rage Against the Machine was fun, especially to play on bass back when I was just starting to learn. Alice in Chains was awesome, though they don't really fit in with the other stuff mentioned in this thread so NVM. The Deftones are also pretty good, though I hated their self-titled. Their new one is actually pretty good based on the two songs I've heard from it. Sevendust is also pretty decent although their last few albums have sounded basically identical. System of a Down has two albums that aren't bad (the S/T and Hypnotize). That's about all I can think of right now.
