Yeah, we [Otakon] got our butts stomped by mail-in Preregistration in 2003... there were thousands of them to type in (literally), and there was only one guy to do it all at the beginning.
After we realized what a problem it was becoming, we were able to get him help to get it all done, but everything took much too much time, and we made too many errors while we were getting caught up.
This year Preregistration is working up some kind of online pre-reg system which will hopefully give us good accuracy and fast turnaround time. Deadlines and cutoff dates have been posted at
http://www.otakon.com, and as soon as the system goes live, we'll definitely be posting something on our web site.