I'm a fan of difficult puzzles (ideally if there is a prize) to the point of sleep deprivation. Let me show you the Isis puzzle. It's titanium, heavy and fits in your hand (but not if you have small hands, then you need two). It's also nearly impossible to open. I'm not giving away any clues at all, we managed it and I'm looking forward to the next challenge.
I'm also a fan of LEGO and this year I was ecstatic to see I had the new LEGO NXT kit. I got bored of the default builds and chucked together this remote control arm in an evening. I'm hoping to improve it and bolt it onto a telepresence robot such as the Rovio.
The additional sensors such as the RFID sensor also look very interesting. I've been interested in cataloging everything in the house with RFID chips and then using multiple sensors to see if we can locate the items in 3d space. That way we would never lose anything :)
The other cool (some may say odd) present was my DNA results from 23andme. I'm not going into detail on the results but it was well worth the $206 and I think everyone should get this done ASAP.