>>26 yeah, funny works too.
But if it's not a girlfriend, seeming like a fag won't hurt. I wouldn't say to MAKE a card, as that can be a lot of trouble, just write your own note in it. Even just one sentence will mean a lot though, one short blurb. Even "I don't know what to write, but I heard it would seem like a better gift if I wrote something, so... <sign name here>"
in the 20 to 50 dollar range, you could also try to appeal to something she likes. as in, HER FAVORITE BAND, NOT RANDOM POP IDL3. Especially if you import a foreign band's album (one she likes of course), or find a rare/old album from her favorite band.
Then there's also the possibility to make a mix CD, find out some of her favorite songs, and burn them onto a single CD. If you're feeling brave/silly/drunk you could try to get a karoke album recorded.
You could also buy tickets to a show that she'd like to see. Try to make it AT LEAST a week after her birthday, so you don't interrupt any other plans. If in doubt, ask her first. It's better to be told about your present ahead of time than have to return it, or worse, toss it.
If you're having a REALLY hard time deciding on a gift, you could ask her what she wants, or give her a few choices of various things. Or just assign random items numbers in your head, and ask her to pick a number between 1 and x.