Ask HN: Visiting San Francisco in August

I run a startup based in New Orleans, and was offered a chance to tag along on a trip to San Francisco for a few days (August 8th-10th) which I jumped on as a chance to look at a far more established start-up community. I've never been to SF, so as an entrepreneurially-minded person, is there anything going on in town that stretch that I could take advantage of? More generally, are there any companies or incubators with an open door sort-of policy that I should check out? This come together rather rapidly for me so I didn't get a chance to do any advance planning, so any advice would be appreciated.