This block offers three different recommendation services: popular activities on this course; popular courses on this site; shared bookmarks. Each can be enabled and configured separately.
Each service displays the top 3 links in the block and a "more" link to an additional page with further recommendations.
Popular activities service lists the 10 most viewed/updated resources and activities within the current course.
Popular courses service lists the top 3 other courses which the current course students are also enrolled upon
Shared bookmarks allows teachers to add any url to the block to make their own recommendations.
The block can be extended by developing your own services.