It's post-Memorial Day, which means it's also supposed to be the start of summer. Maybe the season shift doesn't directly effect the percentage of air guitars, but the nicer weather feels like a good enough reason to believe so, to have faith in good riffs and well-oiled six strings. Rolling Stone fulfills the need -- or at least provides the blueprint for a guitar-centric mixtape -- with a list of the "100 Greatest Guitar Songs Of All Time." As they write: This is what makes a great rock & roll guitar sound: an irresistible riff; a solo or jam that...