I appreciate you putting this together and was about to send the link around when I ran into Application errors throughout. Looks like your server kicked it.
Yes, I see lots of 503s in my Heroku logs :-( This is a pet project, so I don't wanna pay for it, which means you all probably have to live with this until the initial wave of traffic dies down again, sorry!
And it's back. Turns out the problem wasn't really the traffic but a problem with the MongoDB setup...