1) It mimics the sandbox(dropbox) feature in Angel. You can create folder and assign collaborators to each. The collaborators can be assigned different levels of use from being editors to viewers etc.
Students can be invited to view documents , videos or links etc stored in a created folder. They would receive emails with a link to the folder or you could copy the link and send it manually by email etc. Permission, access and security can be set for files and folders.
2) If one has a heavy use of youtube, videos, links etc in their course or would receive documents from students, Box.com does look like it can fulfill that niche with its free features. In essence, it could serve as a great collaborative base or a tranche of extra material for students to access outside of Angel/black board.
3) If WiFi or internet is limited or sketchy for the student or instructor, they could download the Box.com app to an Android device, or iphone, Ipad etc and through the app, be able to download specific documents for offline viewing.
4) Did I mention that you could also install a Box.com add.in (extension) to Office 2010. With it, you can directly create and save, share or open Office documents to folders in Box.com ( straight to cloud) without a browser. Screenshot: http://www.box.com/s/8nrf9btjn1qygslmci9s
I guess it is pretty obvious that on closer inspection I got bitten by the Box.com bug!