Katy Perry - "Extra Terrestrial" (original version, NOT the Kanye West remix) - always makes me think of Lois Lane and her thoughts on Superman.
Kanye West - "Power" - 100% Lex Luthor's theme music.
Spin Doctors - "Jimmy Olsen's Blues" (aka "Pocketful of Kryptonite") - not so much Jimmy Olsen per se, but anyone in Metropolis who fancies Lois but knows about her and Superman being close.
Five For Fighting - "Superman (It's Not Easy)" - honestly, this is how I imagine SMALLVILLE future Superman's thought process.
Newcleus - "Jam On It" - an old school hip-hop classic from 1984, the back half of the song is literally about challenging Superman to a beat-boxing contest. It's hilarious.