Some teaching cases taken from this month's CEP Centrepiece magazine.
1. Selling UK citizenship. We will learn about how markets allocate according to willingness to pay. Here's a proposal to allocate citizenship this way.
2. Complementary goods. If you ban YouTube videos, you might cause sales of music to fall if there are inter-related demands. Exactly this happens.
3. Productivity spillovers. How wikipedia content spills over to benefit others.