Oh man. This is so freakin' difficult for me. You know why? Because so many bands could easily fit into this. I can't name just one, instead I'm going to name a list of powerhouses that I could see myself placing into the category. With each one I place on here, I'll give an explanation for.
Slipknot - Iowa [ 2001 ] - Volume 3: The Subliminal Verses [ 2004 ] - All Hope is Gone [ 2008 ] - They're absolutely revolutionary, and while they were originated in the 90's, what they did with their music, influencing everyone and progressively taking metal into a stage where it entered the main stream to the point where everyone knew who they were, and knew lyrics to at least one of their songs speaks volumes for them. This also lead to others trying out their original roots, and testing the waters for all sorts of music, dropping the barriers of just listening to one specific type of genre.
Skillet - Collide [ 2004 ] - Comatose [ 2006 ] - Awake [ 2009 ] - Another revolutionary band that dropped the walls of Christian Rock and became more mainstream. Playing on the radios of all stations, pop, rock, and other sorts. They're simply amazing and deserve this title by finding a way to effect so many people on so many levels.
Breaking Benjamin - Saturate [ 2002 ] - We're Not Alone Here [ 2004 ] - Phobia [ 2006 ] - Dear Agony [ 2009 ] - Some people would argue that this band shouldn't be up here, saying that they sold out. Some would say that they shouldn't even exist because their music is so terrible. I disagree, they've stay consistent, and their music always has purpose and meaning behind it. You will find music that will touch you by them. Even more so than that, they will blow you away. No pun intended. I do believe that it is debatable that Ben Burley [ Lead singer of the band ] is one of the best lyricists of our generation.
Three Days Grace - Three Days Grace [ 2003 ] - One X [ 2006 ] - Life Starts Now [ 2009 ] - The reason why I chose them as a top contender, is due to the fact that their music is always energized and again the purpose behind it. Also, "One X" has to be one of the most underestimated albums that I've ever heard. These guys are definitely worthy of the status, maybe not so much as others. But listen to "One X" and tell me if you can honestly say that the album isn't under rated. Don't worry, I'll wait for the PM's.
Yes, I know I just classified all rock bands on here. My honorable mentions, however, include.
All That Remains
Avenged Sevenfold
Eminem
Ill Nino
Jay Z
Kanye West
Kid Cudi
Killswitch Engage
Lil Wayne
Linkin' Park
Mudvayne
Hope I don't get flamed too bad for my choices.