There’s a market for everything

This is not a profound observation, but one that is useful to keep in mind: if there’s a transaction that is of some value to more than a handful of people, there’s likely to be a market for it. This is more true than ever in the Internet age, because the costs of finding potential traders, and of executing trades, is much lower than it was just 10 or 15 years ago. The lower the costs of trading, the lower the value of things that will find markets.
One well-known example: text and banner ads that may sell for only a few cents a click.
But there are always new and fun examples. Today’s: a New York Times article about the market for buying Twitter followers. Want to be as popular as Ashton Kutcher?