Had she been 18 (Or 21 if you're in the US) I could have been very helpfull.
Sadly (for you that is), all of my creative, deeply symbolic and meaningfull presents to the opposite six have all been mainly alcohol based.
I had a few of those as well. :hubbahubba: A bottle of Jack always saves the evening...
If you know what music she listens to and if she likes collecting CDs, go for one that's on her wish list. Same for books, I guess you can find something she'd like to read.
If that doesn't work, a nice bouquet of flowers is always a good last resort. Never seen a girl who hates that.
Of course, you'd be the man for all eternity if you could afford a ruby or a sapphire the size of your fist. Though let's assume that's not necessary. ^^