This year, I sent all my relatives a story that my 4-year old son and I made up together and asked them to illustrate it (there are several artists among them and it's the kind of project I know they would enjoy working on together during their traditional Christmas gathering in Colorado). I also informed them that I wasn't sending any other presents but had made a donation to Oxfam. I had hoped that perhaps these efforts would be enough of a hint that they were not required to send presents, but I don't think subtlety is a strong point in my family...
I can empathise with Daylia... too much of a good thing. I think in that situation, you are perfectly entitled to say politely to students/parents that you'd rather they simply gave you a card.
Thanks for all your tips and suggestions... I'll let you know what happens next year! BexMcK