I tried to sign up and received an error:
403: Access Forbidden
This form has not been submitted because your IP is listed in a spam database.
If you feel this is an error, please contact the webmaster.
Tried to contact the webmaster: same result.
Did eventually manage to sign up with an alternative email (non-yahoo)...
Not sure what's going on, but there seem to be some "contact" errors, that may prevent you from getting more sign-ups.