Well, apparently the new user registration link for the forums has been dead for at least the last couple of days. I finally figured out what the problem was and we have implemented a temporary fix that should at least allow people to start registering again. The fix should be made permanent later tonight.
For anyone who has tried to register lately and could not, I really apologize for the inconvenience! If anyone continues to have any issues registering, please let us know. Thanks to those of you who have reported the issue!