Watch the From The iii: Over Minor online guitar lesson by Rob Garland from The Guitarist's Pentathlon
This application introduces an idea I use a lot, playing the pentatonic scale built from a different root note in relation to the key you're in. I'm thinking of Gm7 as the ii chord in the key of F, the iii chord (also minor) is Am, therefore I'm playing Am pentatonic against a Gm7 chord. Of course an easier way to arrive at this is to just play minor pentatonic a whole step up, but don't tell anyone you just found that shortcut, we're supposed to be thinking about the theory here! Playing off another chord in the key such as the iii provides some nice extensions and melodic tones.