Steve Hamaker did the colors for the latest Penny Arcade story arc "The Judging Wood" and made a timelapse video of his work on the final page. It's pretty remarkable to watch.
The early steps where he's filling areas with solid, bright colors is, I've learned, a process called flatting. It's supposed to make coloring detailed objects easier (especially objects that overlap others) by making them easy to separate select with the magic wand tool in Photoshop or whatever. I used some flatting techniques in a handful of Neat Hobby strips like The Eternal Battle but for the most part my linework is too simple and I end up just dumping colors in with the paint bucket tool.