Purchase from exchanges like Bitstamp and Lake BTC and sold over-the-counter OTC to regional customers and vice versa. You may get 8-15% gap per day.
Made large btc purchases from letigitmate exchanges in Europe and China and resold them to customers locally. He called this business “Crypto Coin Capital Management”.
Took advantage of the fact that most of the demand of BTC is ‘to have it right away’ so they´ll go through more peer-to-peer transactions. Buy large quantities and wait whatever is necessary to sell to final people.