Opeth: I am sure by now, some, if not many of you, have heard Opeth before. They are, IMO the greatest band that has ever been. They started off as a Melodic Death Metal band, but now play progressive metal. Even though their style has completely changed, they are still very good. The Vocalist & Guitarrist Mikael Akerfeldt, Has also been involved in other great bands/side Projects Bloodbath, Katatonia, and Edge of Sanity. Even if you don't like metal, you should give Opeth a listen. They are not like other bands.
Isacaarum: Only a few people I know have actually heard them and they are so damn good. They are a Death/Grind band with a lot of potential.
Silent Stream of Godless Elegy: They are totally unique, No other band sounds anything Like them. They have been around for quite some time, and almost nobody I know had even heard of them (before they knew me at least). I can not classify them in a specific Genre. The music is very melodic. They use many instruments that are usually not found in metal. (ie Viola and Cello)
Abigor: Not only are these guys extremely extremely heavy, but they actually know how to play their instruments quite well too. IMO they are the greatest Harmonic Black Metal band around.
Haggard: This band is what happens if you mix classical with Metal. The band has about 20 members and they play a massive variety of instruments. Everything is pieced together greatly and the band just sounds friggin awesome.
and Most Underrated New/Recent Band; The Black Dahlia Murder: I first heard these guys a couple weeks ago, they play death metal the way it is supposed to be played. The drummer is quite skilled and nails everything perfectly. They don't do anything fancy or overly complicated, howeverl they play very very good. They play Technical Death Metal the way it ought to be played.