U2: Songs of Innocence

U2 has been one of those bands with staying power that has gone on for decades.  Since their first album, "Boy," in 1980, they have evolved with the times, with their own unique sound.  At least in my mind, their best work was the albums "Achtung Baby," "The Joshua Tree," and "Rattle and Hum."One could argue they went off the rails a little bit (that may be an understatement) with their technopop sound in the 90's, but they worked their way back to their original sound.

That brings us to their current album, "Songs of Innocence."  Up front, two things made this album already revolutionary: the first is that it was released 5 years after their last album, and the second is that it was released on iTunes- for free.