Account registration now works. It turns out the default Drupal configuration is to disable newly registered accounts and restrict all permissions to administrators. I've changed the registration requirement to e-mail registration, added comment and vote permissions for all users, and closed all accounts created under the old policy. This will give you the opportunity to re-register with your desired username and fulfill the e-mail registration requirement.
I will be vigilant to fight any spam or abuse that results from this action. Please keep in mind that all comments get their links set no-follow when the HTML filters apply, so you won't get Google JuiceTM from spamming your stupid links.