SEAHOP
SEAHOP is an annual day-long puzzle-solving competition based in Seattle, where teams gather to solve difficult puzzles more quickly than their opponents. You can read more about SEAHOP at www.seahop.net, and try your hand at all of the puzzles.
During SEAHOP, teams compete to figure out abstract puzzles that test a wide range of skills and knowledge domains, including literature, cryptography, computer programming, music theory, mycology, and more. As founder and organizer of SEAHOP, I write the majority of the puzzles, but I also welcome submissions from friends and expert puzzle-writers.
SEAHOP 2013 was held on Saturday, June 22nd, and ~25 teams competed, with ~150 participants in total.