There are a lot of cool gifts here but this suggestion for a free gift has to be one of the most thoughtful ever (for someone like me who starts a bunch of things that take him off on tangents!):

Free: ask them what they want to achieve over the next month/3 months/year, and ask if a daily/weekly/monthly call would help them out – if it would, call/visit them at regular intervals and ask them to show you what they have done. Some extra encouragement and motivation is often far more valuable than any product could be, if they are trying to turn a side project into a business.

via Some quick and easy gift ideas for geeks or my Christmas wishlist – Disorganized thoughts.