I really like Mousewait. The times are input by people in the park, and it shows when it was last updated, so you know how recent that time was input. It is the only one I have found that shows the time at which the wait time was input. When I was there my last 2 times I found it to be very accurate.
The only problem is that people can either input the posted wait time, or their actual wait time. And since the wait time listed in front of a ride can be wrong, then so will be the inputed time. (does that make sense?) For example, last time I was there, the Indiana Jones wait time was seldom close, once it said 60 mins and we walked right on. We found that ride to be off more often that other rides, but you get my point.