Over the summer, I remember avidly looking at the archives of Sean Gardner's blog on mornings before work to inspire myself, and it never failed to get me hyped up to go out and draw.
Sean does some of the most outlandish exaggerations I've been lucky enough to see in live work, and his technical ability with Prismacolor Art Stix is unparalleled. He can get some really amazing modeling out of those little things, and it still baffles me how he's able to do it. He clearly puts a lot of thought into color, and uses a much broader palette than most of the caricaturists I know, capturing blues, greens, purples, and yellows people's flesh that many people don't bother to spot when working quickly.
He also specializes in zombie caricatures! This is a self-portrait.
See more work by Sean at his blog.