Much like electroclash, The Strokes, and Williamsburg, Brooklyn, the mash-up was a cringe-inducing fad that defined a few stale months in the early part of our blue-state century. But from the self-indulgent wankfest, one album set a new standard in popular music: Danger Mouse's Gray Album (a combination of Jay-Z's Black Album and the Beatles' White Album). Never one to miss an easy buck, Jigga took notice, and has now released an a cappella version of his brilliant return to form, American Gangster, so that aspirant mashers might somehow net him an extra trillion. First to the plate is DJ Skee's American Godfather, a delicately crafted, download-only mix of Jay-Z's distinctive vocals with Nino Rota's sweeping score and the gritty storytelling of The Godfather.