Danny Choo, who came as a Stormtrooper, was one of many Firefox users who came to Spread Firefox in Akihabara to help promote Firefox by handing out flyers and talking to pedestrians. Danny has uploaded some photos as well.
Cosplay is a practice with origins in Japan that came out of the Anime community where fans dressed up as their favorite Anime characters. The culture is spreading to the US, but Akihabara is one of the centers of Cosplay. Wikipedia has a good article on Cosplay. It turned out that a number of Firefox users were Cosplay fans and showed up in their wear to help out in Akihabara. They were a big hit. The while maid Cosplay thing is very big in Japan - especially in Akihabara. There are Cosplay Cafes and even Maid Cosplay Cafes. The whole maid thing is an interesting phenomenon and isn't as fetish driven as it might appear at first glance.
Anyway, big thanks to everyone who showed up to helps, especially the Cosplayers. (I blogged about my little Cosplay party a few years ago.)
There is a big event in Kamakura tomorrow so if you're in Japan, please come join the fun.