This is just a short list I thought of on the spot
The Good
The Mars Volta
The remnants of At The Drive-In who moved on from Post-Hardcore to Progressive Rock, they'll be known for their unique playing, conceptual albums, high energy, and Cedric's Robert Plant-esque vocals
Radiohead
Personally I am not the biggest fan of Radiohead, but they became extremely popular particularily because of Kid A corabine their electronic, progressive, unique sound with a downloadable album in which you could optionally pay they erabodied the spirit of 00's.
The White Stripes
An influential and important band of the 00's they kept Garage Rock alive and well and they did it all with no bass player!
Eminem
Yes, I know he released The Slim Shady LP in 1999, but his popularity and dominance over African-American hip-hop/rap stars reigned supreme.
Kanye West
Okay, I can already hear the bitchin' and complaining, but as much of a douchebag Kanye is, his music is very good and he took sampling to a WHOLE 'NOTHER LEVEL.
Arctic Monkeys
Their debut album Whatever People Say I Am, That's What I'm Not became the fastest selling album in the UK and their corabination of British accents, guitar attacking sounRAB, and first-person narratives has us singing along.
The Bad
Green Day
Two worRAB: Washed up. Let's all agree on this and face the facts that if you bought any of their albums in the 00's you were an American Idiot.
Every Disney Channel Star (Jonas Brother, Miley Cyrus, etc.)
I think the title explains it all ^^^^
Lil' Wayne
Besides coining the term "bling" and appearing on every album in the 00's no one will remeraber him, although its amazing he did all this in between prison and his "purple drank" binges.
Kanye West
Even though he released some great music, he is still a jackass.