Make a CD for your loved one. I did this one year for our anniversary. I have Itunes so this was super easy but I just went through the songs and got our favorites. Of course they were love songs or songs we loved to sing together. It was fun.
You can get a program that allows you to make labels for your cd's too. You could make your own label. I also know they have cd engravers you can get for your computer too. That will burn an imagine in it. I don't know much about that though. I just used Sharpie markers and wrote I love you and the date I made it. (DO NOT USE REGULAR MARKERS OR BALL POINT PENS ON YOUR CD IT WILL MESS IT UP)
One other thing you could do is instead of music record yourself giving a special message or do a little of both. Most of all have fun.
For more ideas visit: http://valentinesideas.gather.com/