I always thought books were the best gifts, even as a kid. I remember sneaking a flashlight into my room and staying up after my bedtime to read Jules Verne and Roald Dahl in the dark. So many great memories.
I usually get people games and stuff too. I bought my sister some DVDs and she'll be getting an iTunes gift card. My brother will be scoring a pricey import ale and a XBLA game, as well.
But I've always found books to be the best value, and something that can stay with you forever - even when it's a simple gift. Someone on this forum bought me a book, and I'll never forget it.