ToothTag is an app for Android phones that includes a number of very useful location services.
Using ToothTag it is possible to tag things and locations and receive notifications based on your proximity. For example you can tag where you have parked your car so that you can find it again without any problems. The application can also automatically check you in to a number of location based services, such as FourSquare or even alert you when friends are nearby.
ToothTag is built upon NeuAer's powerful Proximity Platform. The Proximity Platform is a lightweight client and hosted server side technology that allows mobile applications on Android devices to add presence events in their applications. The client can be used by Android developers to build their own automatic check-in services or present information to users based upon location.