Tampa,
You have to stop listening to the classical music stations...
Actually, a lot of the ones I listed did really well. Worlld Wide Suicide hit #1, Green Day had a couple of hits with theirs, and I think they got a grammy (or whatever award they give for music) for their album. James Blunt had a hit album, and John Mayer did well with his also.
I talked with my wife about this topic a few days ago - she suggested Black Eye Peas - top 20 or so with 'Where is the love'. Green Day also had 'Holiday' that was also in the top 20. Pink had 'Dear Mr President', System of a Downs had BYOB and 'Boom', and Pallot had 'Everybody has gone to war'. All of those have done very well (according to my wife).
I think that because of all the different types of music out there that there will never be a single hit that stands out as the main voice for or against anything. Rock and rap already had a number of anti Iraq war songs even when the Dixie Chicks were getting blasted for their stance.
Steve