chain tension

Normally I'm a loose chain sort of guy on the fixed gear and I'm always surprised by how loose a chain can get with good components and never come off. Today over on the fixed gear gallery forums I saw this:



Apparently his chain jumped of the chainring and was caught by the crank as it came around. ?!
http://fixedgeargallery.com/forum/viewtopic.php?t=18139

Maybe I'll tension my chain before the ride home.