Some good lists so far. I have to agree with some of those posted already:
Linkin Park (Have fallen off a bit, but still make it for Hybrid Theory alone)
30 Seconds to Mars (REALLY enjoyed the last album)
Florence and The Machine (Florence Welch has an incredible voice)
Some of my own:
Naked and Famous
Paramore
(possibly an ghey but I do enjoy them. Musically very simple but lyrically enjoyable. I really enjoy Hayley Williams, I think she has a unique voice)
Selections like Mumford and Sons and Black Keys are good choices and excellent bands, but are getting to be overplayed and my enjoyment is thusly waning.