There seems to be an issue with the website account creation, I hope this is the right place to report that.
After purchasing the software on steam I decided to create an account here.
I clicked the create account button and then decided to use the facebook option so I clicked that. I got a facebook screen telling me the data that would be shared and then accepted it.
I then got a "divide by zero" error as the only message on the website. This appeared to come from a php page using a "GD" function, but I'm sorry I didn't record the exact message.
However I then appeared to have a half created account. When I tried to log on using facebook it didn't get any error but didn't do anything either. I eventually used the recover password facility to get a new password and at that point it told me my account needed creating (as I'd onl;y logged on with facebook) and everything was fine.
So basically the create account using facebook options does not appear to work and I only stumbled across a way to make it work. It seemed worth reporting as if it's a general problem it might keep people away from the site.