An idea for where you might want to take this would be to turn it into a service for other sites to use. A social networking site webmaster would use your service to offer their users the ability to drag n drop functionality on their page. You would make it easy for the webmaster to create "widgets" that can be added/removed. Basically iGoogle for any site that wants it but doesn't want to get involved in the hairy mess of making a solid and reliable drag n drop interface.