Four years ago Smeal started a national MBA Sustainability Case Competition which we host every fall. In establishing our case competition, we have come to learn about a number of resources for business sustainability cases. Some just supply cases and others provide cases with teaching notes and myriad links to additional information.
In case it saves someone a few steps, here is a grab bag of what we have discovered. There is even more out there and please add your ideas in the comments.
The Case Centre claims to be the case method resource for business education worldwide and to have the largest library of business cases in the world along with teaching materials and a wide variety of other resources such as the Case Centre short video series on writing good cases.