Grid is an Oauth API that allows third party access to our payment network, Dwolla.
In case you're not familiar with Dwolla, we're a cash-based network that is devoid of credit cards (this is how we operate so cheaply). We allow our users to send money through their social networks, buy goods at local stores based on their location (called spots: http://www.dwolla.org/blog/dwolla-spots-the-future-of-paymen...), all for a flat fee of 25 cents.
Grid provides developers access to all of this to build new technologies we haven't even thought of.
Does this help, at all?