Many millions of people enjoy playing online games and for social game developers a hugely important source of revenue is from the sale of virtual goods. The trading of virtual goods within games is a global industry worth over $10 billion a year. Here is a good example of complementary demand in markets - regular gamers are happy to purchase seeds, tractors and coins using real money to help them get ahead in their favourite game. This BBC news feature argues that virtual goods are one of the hottest trends in technology and are fuelling huge growth in the social gaming sector.

There is a fascinating lecture at the RSA early next month - Fun Inc.: Why games are the 21st century’s most serious business - details are here. Tom Chatfield’s new book is available here from Amazon.