The Balanced Ruby SDK by Balanced allows developers to communicate with the API to implement online marketplace payments into applications. Resources available include installation, documentation, and usage.
Microsoft's latest version of its search API (our Live Search API Profile), which was released last November as a public beta, seems to be gaining quite a bit of momentum. According to a recent post on the Live Search Blog, the API is serving more than 3 billion queries per month, more than 5,000 applications to use the API, and queries from third party sites account for 80% of the API's query volume.
There are a number of advertising networks available for mobile applications, but game company Tap Me is creating one specifically for game developers. Tap Me has launched its iPhone SDK today, with plans to support other platforms soon, including a generic API that will allow developers full control of how advertisements are included in their games. Rather than simply provide display advertising, Tap Me ties the ads into in-game actions, with brands able to be integrated deeper into games.