David Letterman is no stranger to lust: This is a man who had so much sex with his female employees that people once held a rally to get him fired for being a pervert. And though he remains a national treasure, his eyes do tend to wander, even today. On Monday night, British songstress Adele got a thorough once-over from the venerable talk-show host, as seen above. It wasn't the first time. Here we present more examples of Letterman not-so-discreetly checking out the female musicians who've visited his show over the years.