possible problem with your site?
http://fancons.com/events/update.shtml/9662
To me, it looks like I could update the details of the con on this page. I don't know if it Would let a random person mess with your listing, but jusst in case thought I'd mention. :> Be safe, be kind.
When users submit updates, they go into a review queue. Every submission is reviewed by a human being before being posted (or rejected). This prevents the site from becoming a spam hole AND also ensures the accuracy of the information. If we just allowed everyone to edit anything with no review, this site would have become useless shortly after it launched a decade and a half ago.