Main Hobbies
Coin Collecting: I collect mainly coins from the United States, though I've branched into modern silver bullion from China and Great Britain (Chinese Silver Pandas and Great Britain Silver Britannias). Visit my coin website for more information.
Photography: My focus with photography is landscapes and starscapes (astrophotography). I don't do people much, though I have a passing interest in formal photography such as wedding and portraits. Visit my photography website for more information. I have also written guides for astrophotography including general astrophotography and lunar astrophotography. And every year (for the past four years) I taught CU-Boulder's astronomy department's Fall workshop on CCD imaging.
Cooking: I think this qualifies as a hobby, though it's much less expensive than the first two ... usually. I generally try to make as much food from scratch as I can; I see no reason to have 15 ingredients in dumpling wrappers, for example. My sub-interest here is with desserts, especially ones that involve chocolate. My home-made caramel-filled chocolates and my truffles go over pretty well when I bring them in to work.
Ancillary Hobbies
Origami: My mom got me interested in origami when I was 5 and I've been doing it on-and-off ever since. For the past decade or so, my focus has been on modular geometric origami, such as designing my own fractal gasket (that's the 3-sided pyramid, or tetrahedron for you math folks) and building a torus. I may post photos eventually.
Web Design: Since 1997, the early days of the web, I've always had at least one website to maintain. Now-a-days, besides my own personal sites (this, my photos, and my coins) I also run my "Journey Through the Galaxy" website and my department's website.
Music: Though I spend very little time on it these days, I still like to occasionally pull out my flute and play.