Yahoo is going open in a big way so that it can enlist third-party developers to make its search and web site portal much more relevant to Internet users.

Yahoo Chief Technology Officer Ari Balogh talked at the Web 2.0 Expo about the company’s plans to enable developers to create applications that will lead to far more customized and social experiences for the users, making Yahoo products stickier than they are today.

He didn’t say this was how the company would fend off Microsoft and stay relevant in the face of big social networks, but that was the subtext.

“We are opening up the assets of Yahoo to developers in a way that we never have before,” he said. “We are rewiring Yahoo from the inside out to create a development platform to open Yahoo’s platforms up to developers. As part of this, we are going to make the consumer experience of Yahoo more social and make the hooks for that available to developers.”

The company announced its “search monkey” platform a couple of weeks ago where developers can integrate their own applications directly into Yahoo’s search results. Today, it is opening up a beta program for search monkey so developers can start creating mash-ups for search results. Developers will be able to customize applications such as Yelp so that its restaurant reviews are much more readily accessible through Yahoo’s search results, he said.

“It gets the user from ‘to do’ to done more quickly,” he said. It won’t just be for search. In the future, Yahoo will enable developers to customize things such as its front page, mail, and other platforms as well.

“Tremendous creativity will be unleashed here,” he said. “Even on the front page. We will allow consumers to put apps on their front page, where those were developed by developers outside of Yahoo. Even with mobile.”

As users navigate to a sports news page, for instance, they can hover over parts of the page and activate third-party developer applications that deliver more news related to a picture or other things on a page. To create apps for the Yahoo front page or mail or other functions, the developer simply creates the app with Yahoo’s development tools. Then the developer selects which platforms where the apps should run. Then they can roll out the app simultaneously across all of the Yahoo properties.

“This is a stylized install screen,” he said, pointing to a screen with a bunch of check boxes. “It will be this simple.”

The search monkey beta is the first step. More releases will come this summer. Throughout this year and next, the results will show up for consumers on the Yahoo platforms. As for the social features, he said, “We are not creating another social network. We are going to rewire the entire Yahoo experience so users can experience a social dimension. We don’t see social as a destination. It infuses everything that we experience on the web. The kind of things we can do with this are endless.”

You can use the “social graph,” for instance, to view messages that are most relevant to you in various Yahoo communications programs. When you visit a news page, Yahoo can “contextualize the experience.”

“That gives you a glimpse of how we are rewiring Yahoo,” he said. “It includes opening it up in a way that we never have before and making the entire Yahoo experience more social.”