I'm so, so, so, so, so excited for Christmas this year! My girlfriend has been moaning and groaning about wanting a massage for months now, so I bought her a gift certificate for a ninety-minute full body couples' massage (among other things that are 100% for her... I always feel like it's weird to buy someone a present that's partially for yourself, but I know she won't go if it's not a joint massage). I think this is the best gift I've given someone, simply because she's been wanting one for so long.
The best gift I ever got was the very first iPod I ever owned. My mom bought it for me when I was in sixth grade, and from the day I pulled it out of the box, I listened to that thing all day, everyday until it literally would not play music anymore.
One year, I had bought my mother one of those really huge coffee table books about old/antique farmhouses (she really likes farmhouses) and while baking cookies with her literally a few nights before Christmas, I said "Man, I really hope you like your book." I realized the second it came out of my mouth what I had said, and ever since then I've been so paranoid when I buy presents this early that I'm going to let them slip.