The ShareThis Android SDK by ShareThis can be used to create file sharing applications. From the site, developers can download this kit creating first an account with Socialize. This means, a different set of Keys will be provided because the company is still working in the ShareThis/Socialize integration.
Just a quick pointer to a fun writeup by Jenny Shank about her husband Julien's experiences of creating and publicizing the very good mashup WeatherMole. The second segment of the story is a great account of the cycle of publicity that many mashups hope for.