I would love to see the song that accompanies the show Smallville "Somebody Save Me" by Remy Zero appear as DLC.
Also bands like:
Dio / Rainbow
Quiet Riot (Bang yer Head, C'mon Feel the Noise)
Twisted Sister (I wanna Rock, We're not Gonna Take it)
Krokus (Screamin In the Night)
Guns n Roses
are all poorly represented and would be fun to do.