This is Green Festival, the San Francisco Spring edition. Insect Discovery Lab has a table at in the Kids' section, and proved to be extremely popular. It's absolutely delightful watching facial expressions as people hold a bug for the first time. Green Fest is like a green expo, with many local companies giving demos and samples, offering specials and such. I collected many green themed magazines: VegNews, Common Ground, Kiwi, Living Crafts, ate much free trade organic chocolate, drank Hemp Protein beverage. It was pleasantly busy, nothing insane like Comic Con. Both exhibitors and attendees were very friendly - I think it was nice to know there was an underlying common value between everyone present.
One more day of Green Fest tomorrow! I recommend a visit (and ask me for a free pass!). Parked a few blocks away in free street parking. The ticket golf-carts (at least 6 seen within 5 minutes!) were out in swarms around metered parking. http://www.greenfestivals.org/san-francisco-spring/