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Vivify [ http://bytefluent.com/vivify/ ] is another good one that takes the opposite approach: Show you code snippets from different languages at once and switch the colorscheme. You can also quickly scrub through the schemes and edit them to create your own.

Good site, found a few there myself.

Fair warning to low performance/feeble browser machines - there are A LOT of images there.

I use vividchalk, which I was happy to see there on the list. It's amazing how many variations on color schemes there are.