I remember watching something on MTV a few years back in which they showed this guy who actually goes out and searches for new music that would fit madden well. But yeah the recent madden soundtracks haven't been too diverse. The last real good one was Madden 04 (a big reason for it is due to its diversity).
Anyways, I have made predictions on who will be on the soundtrack for madden for the past four years and I have gotten at least 2 artists/songs right each year. My sig has my madden 10 soundtrack predictions. I made them based on if the songs are new releases or if they are by new artists and also if their music sounds like something that's suitable for a madden game. So yeah, will see how my predictions go once they reveal the soundtrack