Mashery, to put it simply, helps companies to more easily share their data with outside developers. By making this data more accessible, a company can let other developers use their own creativity to put the information to work.

This technology, called application programming interfaces (or APIs), has been around for years, and has assumed new relevance as more web-connected services look to grow. Auction site eBay has let developers build auction services using its auction data for many years, for example. But APIs are buzzwords these days, and exemplified to consumers by social networks such as Facebook, MySpace and rivals, that let third party developers build applications that access their user information and build applications that integrate into their sites.

You’ll find many web start-ups touting the fact that they have an API. But the real value for an outside developer is using others’ data for their own ends, the promise of more established companies with more established data means more opportunity. That’s where Mashery comes in. It provides support, helping software developers at a company to create APIs for accessing company data in easy ways. It helps a company figure out technical specifications for its APIs, based on the company’s business decisions about what data it does or doesn’t want to share.

San Francisco-based Mashery already has some interesting clients, including international news service Reuters, online real estate site Trulia, online directory Whitepages.com and other corporate clients.

We’ve recently learned that Mashery raised a $2 million round from .406 Ventures, First Round Capital, Formative Ventures Emerging Technologies Fund and angel investor Mark Benioff, who is also the chief executive of online business software company Salesforce.com.

The Benioff investment is particularly interesting, because Salesforce has been busy working with Google and many other companies to let its client companies share their data through its software to others. In other words, Benioff must know that many of Salesforce’s clients have valuable data to share and also want to share it. Mashery is in a niche that serves that need.

Of course, eBay, Google, Facebook and many other tech companies build their own APIs. But as more traditional companies with lots of data develop web properties, look for Mashery’s market opportunities to keep on expanding.