The most common play run in the NBA is the pick and roll. It's simple, fast, and more often than not efficient. Most pick and rolls feature a high screen, ball handler, and three spotted up shooters. Ever so often however, the more inventive coaches will run some sort of off the ball and/or weakside action in addition to the standard PNR. The NBA breakdown site, Hoopchalk, recently wrote about this. Gregg Popovich is one of the most common users of weakside action during the pick and roll. Here's a really simple, but effective example.
Tiago Splitter sets a screen for Tony Parker on the wing in what looks like a standard screen and roll.
Tony Parker gets into the lane, never good for a defense. This is when the weakside action commences. Tim Duncan sets a back screen for Kawhi Leonard in the corner. Wait what? Were you waiting for some complicated flex action to be diagrammed? Nope, that's it. Just a simple little back screen in Leonard in the corner.