http://pictify.me/life/
Eh, it's not great. Certainly inefficient. (I could probably do significant optimization) I wrote it in basically one evening. It doesn't even have an auto-expanding board; it defaults to 100x600. If you want to run a board with a custom size, put it in the hashtag. For example:
http://pictify.me/life/#20x20
Makes a board with 20x20 size.
Enjoy
It takes my computer 11.5 seconds to calculate 100 generations on a 200x200 board (40,000 cells, 0.002875ms per cell per generation).I apologize for the seemingly random domain, it's the only one I have to host it on xD