...and below is where to meet them. Moving here from San Francisco 2 years ago, I've often complained that San Diego culture isn't nearly geeky enough. Slowly but surely over the past few months I've discovered the nerdy corners and nooks of this place. There are lots of interesting, smart, fun, strange people here. In the interest of making San Diego a nerdier place, and to save you the trouble of digging, I highly recommend the following organizations to meet your fellow oddballs, science geeks, metalheads, and deviants:
The San Diego New Atheists and Agnostics - a predominantly social organization that continues to grow by leaps and bounds. Atheist groups are always great places to meet interesting folks. General secular group events (including this one's) are listed centrally at SDCoR's calendar (the San Diego Coalition of Reason).
3RDspace is a cool venue in Normal Heights that hosts groups, art shows, you name it. Look at their calendar to see what's coming up.
Lesswrong - whether or not you're in San Diego, this rationality blog lists meetups for cities around the world, and some have been in San Diego and Irvine.
Sifter - gathers interesting folks and often focuses on exercise and outdoors stuff.
Che Cafe - frequent metal.
Should you decide to go to any of their events, feel free to say it was Mike and his awesome blog Speculative Nonfiction that steered you there. This will gain you immediate credibility.