I have to say, I love Jill Thompson's art. Only a hand full of illustrators use watercolors on a regular basis and she is one of the best at it. I mean, look at these images she did for DC's Sandman.
(images from Gallery Nucleus.)
Now those are older pieces, but this past summer during SDCC, Jill was filmed for the DC Comics Art Academy. In the video she shows how she uses watercolors to get her signature art style while working on a headshot of The Sandman. Be warned, this episode starts rather abruptly and the art is already in progress when it begins.