The Salsa Commons API is a REST and XML API that, as Salsa explains,
"At it's simplest, using the Salsa API may consist of just a form placed on an external website ... At it's most complex, you could use a Ruby library to authenticate, pull down information on recent supporters and events, validate that data, change it, and submit it back to the node, while generating and displaying counts of petition signers -- all through the API."
Location-sharing service Gowalla is preparing to launch its long-awaited write API (our Gowalla API profile). The move could makes its platform as desirable as its main competitor, FourSquare. With it, comes the need to relinquish a bit of control of the user experience, something Gowalla has considered an important factor of its success.