For science geeks like me, there are a lot of really fun shops with neat-o science gifts. Send me yours, and I’ll add them to this list! It can be hard to find stuff like this — if someone wants to start a web-business, creating an online catalog of this sort of stuff would be a great service!
This is my previous co-worker’s site — silver jewelry in the shape of molecules — caffeine (for the coffee addict), serotonin (when you’re feeling blue), oxytocin (for valentine’s day)… they’re really lovely!
For the bio-inspired, this site has clothing centered on evolution and paleontology.
If you google “Science t-shirts” you’ll find a wealth of places online, like ThinkGeek. I’d love to hear specific recommendations.