LinkedIn, arguably the most business-focused social network on the Web, has opened its network to outside application developers with the intent to help its 30 million members (and counting) better communicate, collaborate, and share information."Youll be able to work much more closely with your contacts on LinkedIn with tools such as file sharing, project management, business trips and many more," blogs LinkedIn co-founder Reid Hoffman.

Among the nine new apps comprising the initial rollout are programs that allow users to share presentations, reading lists, blogs, and travel schedules with colleagues -- all of which the company hopes will get members to use the site for more than just job hunting. Another app provides secure online workspaces, which Patrick Crane, LinkedIn's vice president of marketing, expects will appeal to small and midsize businesses.

ZDnet's Larry Dignan's fave? Company Buzz, which tracks Twitter activity associated with your company. "That application could deliver some real business intelligence," he writes on his blog.

Of note, LinkedIn won't allow just any developer to create a program for its network. Each one must go through an assessment process before an app gets the green light, LinkedIn VP of platform Jamie Templeton told CNET News.

LinkedIn, which last week received $22.7 million in funding and has grown in membership by 25% since Lehman Brothers folded Sept. 15, is still on target to hit its full-year revenue forecast of between $75 million and $100 million, according to Red Herring.

More from LinkedIn's Hoffman, plus the apps' developers: