I sold a fair number of bitcoin early on (30-50 IIRC) for a few dollars a piece. I feel like it was the right call at the time (paid for a new graphics card and a few nights out, and a few economics students with whom I was friends and I expected it to bubble and crash completely -- which it mostly did, then has repeatedly rallied after that), but the feeling of "What could have been" comes on every now and again.

Edit: found my Gox emails - it was in June 2012.