I was pretty impressed with the accuracy of this one.
Disney World Wait Times Free by VersaEdge Software.
It has a big
WDW logo, so you can't miss it.
It is volunteer driven, so when you are in a park and approaching a ride, if
you see that the official posted time is different from the iPhone app time, you can update it yourself.
It will tell you how many yards away from a ride you are.
When I'm at home, it tells me how many
miles away I am!
The paid version has no ads, but honestly, the tiny ads don't bother me a bit. I had planned to try the free version and then to upgrade to the paid one, but I'm happy with the free version.
Have a great vacation!