IDG Connect is a great resource for business and IT research. The site, a division of International Data Group (which includes analyst firm IDC), collates white papers, case studies and videos from a variety of sources. Search (for example) for “big data” and it returns 37 white papers from Microsoft, IBM, Symantec, PWC, Oracle and others.
I used some of their research in my recent white paper and they have very kindly posted my paper, “Telling Your Story: Winning Customers with Considered, Compelling Content” on their site.
For writers, of course, IDG Connect is a great place to compare and contrast writing and layout styles for content like white papers and case studies.