Now I been a big Foursquare fanatic ever since fellow G Styler Jason Anderson put me on to it almost a couple years back. Its very addictive in the sense of trying to claim that Mayorship, hold it down and sometimes reap the benefits along with it(aka specials, mayor points, etc). But what happens if say you forget to check-in to a location or you want to meet up with friends and so on. Forecast is a neat app as you can plan your check-ins ahead of time.
You can think of it as a day planner of sorts for your Foursquare lifestyle. Plan to meet up at the Chipotle down the block for lunch? Hit the Bar after hours? See where all your friends are going before they get there. I think its also a cool app if you happen to get to a location and forget to check-in as you will get a reminder when you hit the time you set. Tell me that has not happen to you numerous times already. Also whats cool you can check-in right from the app itself.
Forecast is available in the Android Market and iPhone App Store for free. It is currently in private beta. But if you have a Foursquare friend using the app your automatically in, otherwise you can request a invite.