Good article by Jon Udell on "Overcoming data friction". One of the projects in my course this term is trying to do something like this by gluing together data from various social services' web sites --- screen-scraping and after-the-fact duct tape turns out to be easier than getting various branches of the same government to agree to exchange data, or make it available to the public that's paying for it. Students interested in startups, take note: any information that's hard for you to get or correlate is a market opportunity.