MAKE Magazine has posted an interesting gift guide for open source hardware & software.
I thought that many of the items listed were rather rather interesting and may even try a few of the projects that are listed (e.g. the mp3 player kits).
I also highly recommend donating to the Electronic Frontier Foundation (EFF) and becoming a member. MAKE lists the $100 pioneer membership, but you can give them anything you want. It is for a worthy cause after all.
If you are interested, MAKE is also encouraging people to comment on the guide and tell them about some more items so they can add them to the list.