I've been running queue-times.com for nearly 2 years now, user submitted times are simply not going to work unless there is a reason for a user to update the waits (i.e: money). I just use the parks own data sources, which are updated regularly and tend to be fairly accurate (although you should take them with a pinch of salt). I'll be interested to see what data you manage to collect on your site - I'm happy to be proved wrong.