I work part-time drawing live caricatures at a very popular theme-park. It's an amazingly fun and challenging gig in all aspects, and I recommend it to anyone looking to improve their speed, calligraphy, cartooning, understanding of facial anatomy and structure, gesture, silhouettes, composition, or overall drawing skills. If you push yourself, it's not just a cute kid "in a dune buggy - cuz everyone loves dune buggies!!!" - one can achieve many goals by this incessant practice under pressure of the public (as frustrating as it can be, at times).
Anyway, I love caricature and portraiture, and I've got a running blog (mostly for my own entertainment) of my live work and other sketches, to keep me motivated, honest, and working. http://joebluhm.blogspot.com - My latest update are of some sketches that I've done from magazines and photos while killing time in the theme-park. They're quick, but fairly fun.
Here's a couple samples... There are plenty more in my blog: