If you're thinking of songs they play over the loudspeaker at Kinnick, you will definitely need Back in Black and Enter Sandman.
I've also heard these gems on third downs: Thunderstruck, Hells Bells (both ACDC), Kickstart my Heart (Mötley Crüe), Riot (Three Days Grace-pretty sure that's the one), Animals (Nickleback).
Also, Start me Up by the Stones for the kick off.
And maybe you'll want to add the Poncheros Pump it up song.
Those were just the ones of the top of my head. I'd be interested to hear what the others have to say on this subject.