If you don't mind the whole screaming/growling vocals thing, I'd recommend Between the Buried and Me. They put out an album last year Colors that definitely made my top three for the year. Also, I'm surprised nobody mentioned Opeth, one of my fav bands of all time, brilliant stuff.

Oh, and Mastodon is great too if you're not into the really brutal stuff.

I wouldn't really consider Between the Buried and Me to be mainstream metal... but I also consider mainstream metal to be the stuff on the radio that isn't really metal. But yeah, Between the Buried and Me are great.

I don’t know if anyone on MC has heard of an Australian band called The Butterfly Effect. I’ve been listening to their most recent album entitled Imago for the past year, and I’m still loving it, however I probably wouldn’t peg them as a mainstream band. Again, I don’t know if you guys haven’t already heard of this band, but another album I’ve been listening to a fair bit lately is Themata by Karnivool, which is also an aussie band.

It wouldn’t surprise me if most folks on MC hated Creed, but I recently had a listen to Alter Bridge, which for those of you who don’t know, is Creed without Scott Stapp, or at least I thought it was going to be. I was really surprised at how heavy and progressive they are. The general quality of the 2 albums they’ve made as Alter Bridge far exceeds the bulk of their work as Creed, or at least in my opinion. Some have said to me that the name “Alter Bridge” has warded them off, due to thinking that the lyrics would be crammed with constant religious connotations, but after listening to both albums One Day Remains and Blackbird, I’d say that the lyrics are more personal and open to interpretation. Another thing I’d note is that Myles Kennedy (lead vocals and guitar) is a highly diverse and accomplished singer.

If you’re interested, all the links go to the bands myspace pages, where you can preview their music.

I just received The Pax Cecilia CD. Very different from what I expected (last.fm lists Circle Takes the Square as a similar artist!?), but I'm liking it so far. The one thing is that I wish the vocals were mixed louder, can't understand them at all. And I feel like these guys do have something to say. Maybe I'll see if they have lyrics online.

I'm not sure if Kataklysm is mainstream, but they're worth checking. Then Dimmu Borgir, too.

Both Thrice and Dillinger Escape Plan's 2007 stuff that's already been mentioned is fantastic - can I add Fear Of The Left and Biffy Clyro into that mixer?

Parkway Drive

flatline scream vocal, maiden-esque dual guitar thing, blast beat drums, but overall pulled off very tastefully.