[mturmon]

Hmm...the linked page worked for me on several tries for 16, 20, and 22 colors, even restricting the luminance somewhat.

I used the protovis categorical colors (http://mbostock.github.com/protovis/docs/color.html, see at the bottom of the page) when I needed a 20-color map recently.

[ChuckMcM]

Those are nice, I've bookmarked the protovis ones. Re-running my experiment, I seem to get two nearly identical magentas or two nearly identical greens every time I re-roll. It is entirely possible its my monitor though.