Composer Darcy James Argue sent out a tweet that piqued my interest over the past weekend. https://twitter.com/darcyjamesargue/status/457670302273912832
He then proceeded to retweet several great responses. I've listed as many as I can here for a quick reference; partly because I think that everyone should see the true value of Twitter, and partly because I am a lazy blogger who struggles to update with more original material.
There are several more great mentions that you can find in @darcyjamesargue's feed. I suppose the only major missing example would be Louis Armstrong's dramatic 1928 reinvention of "West End Blues".
I've made a (partial) playlist here for easy reference. Enjoy!