Mix tapes (I guess cd's now keeping up with the ages) are always a winner. Spend LOTS of time picking out good MEANINGFUL tracks, and be creative with art on the tape/cd AND the case. Make sure it has a theme that is important to HER, and possibly your relationship. This is a birthday not a anniversary, but it depends on her. She may want it to be a day about her, or a day about your relationship or a day about overall fun, who knows. Thats where you being her b/f comes in. Anyways... mix tapes are a fun gift to make, and they really show you were thinking if you do it right.

Make sure to write her a card, and if you do a mixtape explain why you choose what songs you choose and how they fit the theme bla bla bla. Avoid making the whole tape sappy love songs, unless thats the theme. She will only use it in sappy love song situations, which means less props for you down the road. If you include a wide assortment of good songs that fit a theme, she will listen to it all the time, and if you explain how the songs fit the theme, then she will think of the theme, and you when she hears the songs. This creates strong emotional ties, and she will love you for it.

To review mixtape = best high school g/f gift EVER.

If you don't have time/energy/resources for that. Get her a stuff animal at the mall, maybe roses, and write a HUGE ass letter to make up for your generic gift. Of coarse don't mention in the letter you are making up for your generic gift.

Good luck, and let us know how it turns out.

Edit:
Getting her a pipe would work as well, but if shes not a hardcore smoker it may be kind of an odd gift. I know I would dig a new piece, but I'm not sure how the casual smoker would feel about it. Especially if they were expecting something more meaningful. You may come off just as a fiend who even in your relationship can only think about bud. I would say, unless shes is a big weed head, give her something else in ADDITION to the pipe.