HeyZap already offers a range of social and virtual currency features for developers who build games using its Flash browser plug-in, and today it’s rolling out a new one: A dual currency option. This could be especially valuable for casual game developers who have their games published across the web.

Many social games already use this concept, of course. Dual currencies typically include both a currency that costs money and one that can be earned through actions within a game — although specific implementations vary widely. Generally, the free currency lets users who don’t want to pay (or can’t pay) still progress in the game, which hopefully leads to more people playing more often. As long as a consistent portion of users pay in this system, the free currency can eventually help the developer make more money.

In Heyzap’s implementation of the dual currency, users pay or take offers to get the “coins” currency, or gain achievements or share the game with friends to earn the “points” currency. Either way, users can buy the same set of virtual goods.

HeyZap has been busy pushing a string of iterative features for its service. Back on August, it began giving web site owners the ability to earn money from games they run on their sites. In late October, it launched an analytics service, and an application programming interface to let developers integrate social sharing features from Facebook and Twitter into their games. These features are now integrated with the dual currency, co-founder Jude Gomila tells us.

The company launched eight months ago and is currently running 10 million game plays a month across 100,000 web sites; publishers include ebaum’s world, webs.com and College Humor.

Social games on Facebook and other social networks have tended to dominate in terms of numbers and revenue. And, since most games on social networks have been built in Flash, they can also run Heyzap’s services — although a wide range of other companies are competing for those developers, and many developers choose to build their own virtual economies, anyway. So Heyzap, like rival Mochi Media, has been focusing on casual game developers, trying to make it just as easy for this sector of the gaming world to become more social, grow and make money. That market is more mature, and not as currently dynamic, but new services like these could give it a boost.