A lucky art collector who bought a chalk portrait in 2007 for a measly $19,000 could have it reappraised at as much as $100 million after finding a fingerprint that some say proves it's a work by Leonardo da Vinci (at the very least, he probably touched it, say experts). This would be the first discovery of a previously unrecognized work by Da Vinci in 100 years, so it seems to have been a wise investment. [Antiques Trade Gazette via ArtsBeat/NYT]