Here's the first public release of GeoMata (my ADC I entry). The concept is very simple, we provide an open REST service that maps geographic locations to web content (audio, video, html), and a mobile client for accessing this data.
The GeoMata android client displays these "blips" either on a map or in list form, sorted by proximity to your current location. A typical usage scenario might go something like this: You're standing next to a monument of some historic person. You launch GeoMata on your mobile device, GeoMata uses the devices GPS to query our service, and then gives you a list of available web content, perhaps a wikipedia page pertaining to the person or monument your looking at.
The hardest part about a service like this is gathering all the data to make this a really useful application. We bootstrapped GeoMata with over 140,000 points that link to Wikipedia, which is a good start, but we are hoping end users will add content as well. You can create a new "blip" right from the device itself, associate it with some web content (and audio file, an mp4 video, or a web page), and share it with the rest of the world. We are giving the client away for free, and we intend to open source everything sometime after ADC 2 ends.
I invite everyone to visit our website and download our client from http://www.geomata.com/. Criticism, suggestions are welcome!