For the last four or five hours, the site has been more or less unusable. Something went awry with google appengine's servers so all appengine sites were affected. I'm working to make our site show something better than a generic error page when that happens for next time, since it does happen from time to time but pretty rarely, and the google guys fix things pretty quickly.

If your weren't able to study because of this and you are either on your free trial or paid, send nick or me (nick@skritter.com, scott@skritter.com) an email and we'll credit you an extra day.

Thanks for your guys' patience!

Thanks for the heads up!