I've run across a number of people who, like me, have been looking for people to explore with. Earlier this year I set up a Facebook group called Misplaced Places (http://www.facebook.com/home.php?#/group.php?gid=73011188640
) to put together outtings, etc.
Right now it's about 80% west coast/SF Bay Area, but if anyone else would like to use the group as a way of setting up events and finding people to explore with, feel free to join the group.
If you want to set up events, send me a message there (Geoff Tuffli) and I'll set you up with event privs on the group as well.