Watchee is a SOA platform to connect mobile devices like mobile phones, PDA, iPhone and backend services. An open API is made available in many programming languages. The web access is http://watchee.net
GeoPress is the world's first entirely OpenSource Geo-Tagging Platform....
Install GeoPress on your own server, create maps, places and start checking-in. You can create both private and public places, leave full HTML content for both checkins and place descriptions.
However, please note that
... [More] at present, GeoPress is in an EXTREMELY alpha state. It has been released now to the public not only as a way to demonstrate what is possible with BackPress - http://backpress.org - but to more importantly get people to start thinking about the importance of such a platform. [Less]