I believe reviewing case studies is an excellent way to learn more about the industry (what all the cool cats are doing), generate some new ideas of your own and learn from others mistakes.
Besides the Award sites such as the Webbies, Cannes Lions, One Show Interactive Awards, etc. – here are some other useful sites for interactive/digital case studies and client problem/solutions:
http://www.facebook.com/akqa#/akqa?v=app_2392950137 (not all are case studies but there are some good examples)
More to come later – I will keep expanding this list.