SketchCrawl.com™

I've used and like Derwent. You can also find, if you look, a brush that holds water in the handle - also good for travel. It comes in, I think, 3 different sizes. Don't recall the brand name, unfortunately.

Agree with the Micron and Sharpie recommendations. I've also had good luck with Pilot gel pens.

Hi - I'm Chris. Surprised to be the first Chicagoan here, so far as I can tell. Stumbled on it myself when a friend's sketches popped up on Facebook. Shall be interested to see how this works.