When the Levee Breaks

I was listening to Zeppelin IV tonight and decided to look up "When the Levee Breaks" on Wikipedia. As it turns out, it's a remake of an old blues song originally by Kansas Joe McCoy (predecessors to Gnarls Barkley in using one name for a duo). Further inspection revealed this archive site with free MP3 downloads of the original song. Ah, the glory of Wikipedia...