If your parents might follow through on it, one of the things I have found works really well is asking for family history - typed up files (files are easy to store!) with stories of the family - your childhood, your parents' childhood, any stories they may remember of other relatives who are dear to you, etc. Family photos are a nice one if they feel the need to give something physical. Another of my friends plays the "I really need (X practical thing, ie new washer) - the one I want is at Sears, so a gift card there would help me get this and be great" - because then they feel like they are getting her something, but they know there's a specific one she wants to they don't just dump a random one on her. (This only works with some parents, obviously....)

I also have found with my "must give actual gifts" in-laws that a wish-list listing what I want, down to the exact brand item, works fairly well. It feels less spontaneous but at least I can use what I get. :)