It really depends on what kind of music you're into, and how you categorize it. I'd define most of what I listen to as (hard) rock or metal, but some people might define it in other ways... But then again, I listen to lots of different kind of music

Some bands I really like:
- Sevendust (Animosity album)
- Stone Sour (rather than Slipknot, more melodic imo)
- Tool (greatest band EVER! Quite complicated and time consuming though. Check 'em out)
- A Perfect Circle (Maynard's [Tool singer] other band)
- Ill Nino
- In Flames (Melodic death metal from Sweden, check out their Reroute to Remain album)
- Chevelle (a bit like Tool imo, but simpler)
- Coheed and Cambria (named the Rush and Led Zepplin of our generation by some)
- HIM (slightly out of category, but great)
- Deftones
- Machine Head
- Rammstein
- Muse

Also, I'd suggest everyone who likes rock to check out a british band called InMe, at least their first album, Overgrown Eden...