Merlot II offers a repository of materials that are contributed and reviewed by educators worldwide. The site is administered by The California State University, and has been collecting resources since 1997. This is a true open resource, with an active and generous following. Instructors can use the materials without logging in, but free membership includes the opportunity to review posted materials and keep a bookmarked collection of your own favorites.
To provide an example, I did a quick search with the term “business” and turned up a tutorial, “Guide to Financial Statements.” I can see from the resource summary that the material is highly rated and has been updated recently (June 2015). In addition to tutorials, the search returned case studies, videos, and animations, which can all be sorted by the date modified or highest rating.