I posted a note flogging our new Bay Area focus at Tribe.net’s Bay Area Hiking tribe and got a reply from a guy offering to lead anthropological hikes around the area. Of course the best place to study humans is at a crowded bar with the music blasting; what you learn about people in the wilderness is their tendency to foul it up, but anyway, I’m thinking this might be a good place to find some folks to hike with. (Tribe’s vibe is sort of willfully funky — think Burning Man — which is fine in moderate doses.)
Meetup.com has a pretty slick interface for matching regions and interests. At the home page, you type in your zip code in one field and your interest in another and voila — folks in your neck of the woods who’re into the same stuff (this may force you to confront the fact that whose who share your interests are, well, much like you, but nothing’s free in life).