The folks over at Make magazine are nutty and brilliant. Witness their open-source gift guide, inspiring for the electronics geek in us all. It's not the guide that's open-source, it's the gifts themselves: They're all hackable, and they're also (largely) on the cheap.
In essence, it's an irresistible gift guide for the serious tinkerer. Make your own LED menorah, modify a teeny Linux computer to your heart's content, or start your four-year-old out on her very own microcontroller board.
Read the fine print at Make: "Open source hardware gift guide"