I am self-taught on guitar, and I love pretty much all styles of music. Lately I have been getting frustrated with my normal practice, and realize that the best way for me to progress is to play with other musicians. So to do this, I have decided to audition for my school's Jazz band on guitar (I also play Baritone Horn and Trumpet.) The thing is, that the audition piece is my choice, but I don't know much about Jazz guitar. I enjoy finger-picking, but can play with a pick as well. I am still a beginner, but I can play most intermediate tunes (I can play "hey hey" by Eric Clapton...that gets me some points right?)

So if any of you know a good Jazz song for solo guitar, or one that would sound good played alone, please post here.

Thank you very much,
Misty by Joe Pass is a good one.

You could probably arrange a nice version of Round Midnight that would be real nice.

If I were to do it, though, I would go for a performance similar to Monk's version of Just a Gigolo
As a guitarist, you have the luxury of being able to play more than one note at a time. If you can pull it off, try doing a chord-melody arrangement(playing bass, chords, and the melody at the same time, look up videos of Joe Pass for examples) of a tune, or finding one online tabbed out if you absolutely must. Simple, generally considered "beginner" tunes are Autumn Leaves, Misty, and All The Things You Are(among others, of course).