What do you get when you combine a thousand dollars, an unemployed friend, and Charlie Munger's sharp insight? Passive income that lasts for decades.

In 1962, long before his fame at Berkshire Hathaway, Munger partnered with Al Marshall, an unemployed oilman, to buy mining rights at a public auction. Each invested a thousand dollars in what was then known as the tax-exempt AB trust fund (which was later banned). The result? Income from oil revenues that lasted for over 50 years - and it was said to have reached $100,000 a year at one point.

Marshall later said, "Perhaps we each made half a million dollars from it." And decades later, he was still receiving monthly checks.

What did Munger take away? These opportunities are rare - when you get a chance, act quickly. He said, "The trick in life is to do something about it."