[ChuckMcM]

This is an interesting tool, it fails at 16 colors. Which is surprising. (it may be the gamut of my display of course but I would think 16 would be within its abilities). That is probably the most number of distinct colors I've needed in a graph. Works nicely for numbers 10 and below.

[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.