Interesting niche that I know many would love to see filled by Foursquare et al. [Forecast](http://foreca.st/) is a mobile application (iOS/Android currently) that lets you tell your friends _where you will be_ and _when you’ll get there_. Then, when you arrive, you can quickly check into wherever you are via Foursquare.
/via [Brian Shaler](http://brian.shaler.name/).
