Cover songs aren't just something we hear at the local bar on slow weeknights. Artists, from small-time garage bands to chart-topping divas, all participate in paying homage to earlier songs. Some of them end up so good, that people forget there was an original, others remind us of a good song that's been forgotten. Then there are covers that take a different approach to a song, allowing good ideas to spread beyond one genre of music. These are 20 such covers that managed to live up to their originals, or even outdo them.