What kind of audition? Either way you could check out www.wsmamusic.org. Its the wisconsin solo ensemble list. Click on festival lists, then 2008-2009 festival music list. If you want to avoid downloading the list just go to the search database by section. There's two main events under vocal solos, a more classical one, and a musical theater one. You should be able to dig around and find something nice.

Sing "Singin' in the Bathtub". It's not too difficult to memorize, but it was written in like, 1930, so the hardest part will be finding it. It got me into the top choir at my school, and it gets lots of laughs while showing off musical talent.

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Wait a sec, this is for college? Oops...perhaps not that one then. How about "Homeward Bound"? It's very popular because of its musicality and expressiveness. It would most likely be in your range. Or perhaps "On the Banks of Bonnie Brae". Very nice song.