Foursquare is location-based game where users compete for mayorships of locations such as bars, nightclubs and hotels and try to earn badges and get points for checking in more places. At present the service is primarily used through its iPhone application right now, but the service is expanding to Android, Blackberry and should make it to Windows Mobile by next month.
Foursquare has been using the location information to alert users when there is a deal at a venue nearby. Right now, these deals are centred around â€œmayorsâ€ of places, meaning if a person has checked-in the most times at a location. Some venues are starting to offer deals like free beer to mayors, as it obviously benefits them to get people wanting to come back more to check-in.
At present an unofficial Windows Mobile app is under development and available here.