[Video Link] Judging from the trailer here, A Grain of Sand looks like a good documentary. You can watch it here for $3.
On a whim in 1962, British newspaper editor Brendon Grimshaw bought the tiny deserted Moyenne Island in the Seychelles for £8,000. In 1972 he moved to the island and has remained its caretaker ever since. Now 86 years old (and yet remarkably spry and fit), Grimshaw has planted 16,000 trees and reintroduced giant tortoises to the island (see this BBC clip on Grimshaw). Developers have reportedly offered him $50 million dollars or more for the island, but he has always refused to sell. The island is now a national park.
(Via Laughing Squid) Previously: 86-year-old lives alone on island he bought in 1962