But I don't have a username, I've got a security question and answer!

Vancoufur has switched from question/answer logins to username/password logins. If you have an existing account using question and answer, click the "new user or lost password" link above, and enter the e-mail address that matches your existing account. You will receive an e-mail that will allow you to "claim" your old account, and create a username and password for it.