From cnbc:

Passing through Giltner, Neb. early last August, farmer Mike Haley used his Twitter account to post a message, or tweet, about a particularly robust corn crop.

“If I was @zjhunn or @cornfedfarmer I would be smiling, best corn iv seen is their area!”

What may have seemed like a passing compliment turned into a $200,000 profit.

The harvest belonged to brothers Zach and Brandon Hunnicutt—known on Twitter as “zjhunn” and “cornfedfarmer” respectively—fifth-generation south central Nebraska farmers who raise corn, soybeans, and popcorn on their 3,500 acres they share with their father and neighbor.

For more, see: How Twitter Is Transforming Trading in Commodities