For my last few birthdays, I've had friends over for pizza, cake, a movie, and maybe a game (like Cranium, or Imaginiff). Heh, I'm not much more creative than that... nor do I like to drink all that much (my friends like it even less)... but I just realized I'll be turning 22 in less than two weeks!
Just thinking back to high school, I remember one of my friends had a karaoke party. I did a sleepover one year when my birthday was on a Friday. My 14th birthday was the second week of grade 9, my first year at high school, and one of my new friends threw me a party at lunch; she got a big card and got everyone to sign it, and organized the purchase of pizzas, and we all sat outside to enjoy ourselves. At the end of that year, I found a picture of us at that party in the yearbook.
My last birthday party with my high school friends was a combined party with one of my friends born in July. We held the party in August, a couple of weeks before we all went off to uni. We did one of those murder mystery dinner games. Heh, my 19th bday (which is the legal age in most of Canada), I went out to dinner with a couple of close friends I'd made since starting uni, and I bought a glass of wine for the sake of it. Though, I'd technically already had my first legal drink a month before, in one of the three provinces where the legal age is 18.
Meh, I hope that you find what you're looking for. I've given a few suggestions in all that chatter... in any case, do something you'll enjoy, and have fun with it!