You could fairly accuse Rebel Records of making a money move here, releasing this compilation of Ralph Stanley songs in the wake of the successful film O Brother, Where Are Thou, during which Stanley sang “Oh Death” in a pivotal scene. But mercenary or not, this collection brings together some of Stanley’s most hair-raising performances: of course, his rendition of the title track leaves the movie version in the dust, but “I Am Weary (Let Me Rest)” and — especially — “Angel Band” are even better.