So a friend writes me that he's dropping by tomorrow and he wants to play random song X.
So, I go to YouTube and record it into Sonar.
I convert it to midi using melodyne (Editor version) and find the melody.
I drag it into a midi track and feed it into Strum Acoustic and watch the chords go by with the changes.
I sit with my guitar and just have a great time playing the song fairly faithfully.
I'll be ready when my friend drops by.
Couldn't be simpler.