A couple of acts I've been following musically lately are Sara Bareilles and Florence and the Machine.
Really love both their versions ... (and so different) of the old Beatles hit, "Oh! Darling". I went on a hunt for the Beatles doing this song in concert, and was surprised not to find any footage. Usually, if you can't find the Beatles doing a song live, you can find a later version of McCartney doing it solo. Not in this case. But, for contrast, here's the original version cut with a great selection of Beatles photos. Abbey Road was my second favorite Beatles album, after "White".
The YouTube versions for Florence can't be embedded, and give her audio version with just a still. But her version is so damn bluesy and special, I included a link.
Lastly, this was my favorite performance from "Across the Universe" with Dana Fuchs and Martin Luther McCoy.
The incomparable Florence (Welch, with the Machine):
Across the Universe:
And, the original... fabulous: