Site builder Webs.com (formerly known as Freewebs) is launching a new App Store today with the hopes of helping its members customize their sites with rich, dynamic web apps without having to deal with widgets. The company is adopting a model similar to Facebook Platform, inviting developers to build applications that users can install on their Webs.com pages from a central directory.Webs CEO Haroon Mokhtarzada says that one of the biggest problems with traditional website builders is that they generate static content, and it's up to the site owner to continuously provide new content in order to engage readers. That's fine in some cases (like for business websites), but most people have a tough time coming up with quality content on a regular basis. But he says that rich applications, which offer users a more dynamic experience, can help.