Heres a couple more for you......
A gift card to download music off of the internet when they are at college.
You could also do a small scrapbook for each of them.
Are the girls close? You could take them somewhere and have their picture taken together and then buy them each a copy of the picture. One with them wearing their uniforms would be really cute.
They can always use cute stationary, stamps and envelopes, along with a disposable camera to keep in touch with each other.
Hope this has given you some ideas.
Im going to move this thread to the "Gift Giving Ideas" forum to see if we can generate some more ideas for you.
If you still need more help, just ask!
Let me know what you decide to do.
Tami