Mind you, this is ultra-alpha software that most likely simply will not work. Also it is hosted on the awesome heroku node.js beta setup which means you might get hit by the pretty narrow request limits.
Anyway, I think it is fun already, so here we go.
Just click here and start shooting at this page. If somebody else is here as well, you should see them shooting as well. You can also take the above link and execute it on any page as a bookmarklet.
To make this more fun, here are some targets: