On this snowy Saturday morning (first significant snow here since last Halloween!), I was listening to an archived version of NPR's Science Friday from January 13. They were interviewing Carl Zimmer about his Science Ink: Tattoos of the Science Obsessed book.
Zimmer, a science writer, started collecting images of science-themed tattoos on his blog (The Loom). This eventually led to a book (that's how to write a book, ask people to submit all the material you need). Here are some examples. They're interesting to look at some are pretty neat.
Anyway, I'm mentioning this because when the host Ira Flatow asked Zimmer what types of tattoos he needed more images of, Zimmer answered geology related tattoos!
It seems to me there are a lot of possibilities there... Interesting extinct organisms like Anomalocaris. You could tattoo a globe showing Pangaea. A crystal form. Maybe a simple rock hammer (Zimmer mentioned an archaeologist who tattooed a trowel on themselves).
I don't have any tattoos (I'm not a very trendy person), but who knows. Maybe my current mid-life crisis will lead to a cool tattoo after a few beers some evening.