iOS: If you want to know how long you'll be waiting for your next table or how long it'll take to gain access to a club, just search for your destination on WaitList and find out.
Thank The Onion's A.V. Club for this one. If your iOS device has a GPS signal you can find all sorts of places near you. If not, you can always search for what you're looking for or just navigate to the area on the map. When you find one, if it's reporting a wait time you'll see a number in it's little map pin/bubble. If not and you head there anyway, WaitList lets you report wait times.
Clicking on a location gives you a little more information, see the wait times people are reporting, and report a wait time of your own. Probably because WaitList is pretty new (or because I checked after most places were closed), I wasn't able to find any reported wait times (at least in Los Angeles and New York). At the moment the app is more useful in theory than it is in practice. It's also the sort of app that's made useful by its users, so until restaurants and bars start reporting their own wait times through WaitList you can help make it more functional by contributing.
WaitList is a free iOS app available now in the iTunes App Store.
WaitList [iTunes App Store]