Jambool, the parent company of micropayment platform Social Gold, has raised $5 million in a funding round led by Madrona Venture Group, adding to the $1 million it raised in late 2008. Bay Partners reportedly also participated.

Social Gold enables developers to easily implement a micropayments system into virtual worlds, social networking games and similar engagement offerings. Its suite includes an in-game payment system with support for credit cards, mobile payments and online transaction systems like PayPal; as well as a virtual currency system and a set of analytics tools for developers seeking to track their in-game ecommerce.

The term "micropayments" refers to the small transactions users make, typically to send each other virtual gifts, which on Facebook can cost one dollar, or credit virtual worlds or gaming accounts.

Jambool's origins lie in social network games development. In 2008 it focused more heavily on microtransactions, a lucrative niche that is less crowded with competitors.

The company said its investment funding will be used to develop a subscription product for the near future, as well as more self-serve options for developers with an eye for ecommerce.

The micropayments industry became evidently lucrative around 2004, when a Peppercoin and Ipsos-Reid study showed that about one in six people claimed to have used credit cards or other non-cash means to buy something for less than $5 over the internet. The trend has given rise, in part, to aggressive virtual economies. This generally-unregulated sector has become so active that some governments, including that of China, have begun examining ways to maintain virtual order with real-world consequences for abusers of the system.