Well, maybe a bunch of photos will do? If you've been friends for a long time and you have shared memories, then you can probably collect some photos of you two and print them out or give her a photo book. I know that Shutterfly does that. Or, if you don't want to give her a gift that is a thing, then make a slideshow out of your photos and she can re-watch it whenever she wants, too. I'm not a great expert when it comes to all the computer stuff, but I know that Smartshow 3d is a rather good program for that, my DD used when my DGD was turning 18, and we've got a very heartfelt slideshow at her Birthday party. Probably your friend would like it, too