I've uploaded many fixes to registration.fanime.com that should fix several of the problems people may have had.
In particular, if you tried to enter a Zip/Postal Code that was not in the American style "12345" or "12345-6789" formats and got a crash page, you should be able to submit the form now.
Also, if you were one of the handful of people that tried to create a new account around 3:30AM-4:30AM this morning (2010-11-06), the major crash bug you got has been fixed as well. I accidentally uploaded the wrong version to the server. :(
Sorry for the trouble!