For me choosing color scheme for anything is always a challenge. I can recognize good one, but making one form scratch is pain. There are many tools that boil task down to color wheel and some basic theory – I find approach lacking.
Colorbrewer is a specialized web app on color schemes for maps. With many advanced features that really give it edge as general-purpose schemes source as well.
What it offers
Site is done completely in Flash, together with all relevant textual information. Result is snappy and works good with extensive preview map. 
Instead of color theory site emphasizes nature of data represented and that colors remain distinguishable in any proportion.
Strong features
Aside from data-driven approach there are also good accessibility options. Schemes can be limited to those that will look fine:
- to colorblind people;
- printed in color;
- printed or photocopied in black and white;
- any combination of the above.
Results can be easily exported for use with Adobe products or simply as text set in RGB, CMYK or HEX.
Overall
I don’t know just how happy this site makes people who actually use it for maps. But it worked excellent for me when I needed to built set of extensive diagrams and pie-charts in same color scheme.
Color schemes site offers may not be very flexible but it guarantees excellent looks and usability.
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“Instead of color theory
site emphasizes nature of
data represented”
.
Can you elaborate a little on the above ?
I’m not seeing the data emphasis.
.
The DataRat
.
@DataRat
Color theory approach roots for colors that go well together. Like opposite colors on wheel (red-green, blue-yellow).
Colorbrewer’s task is not to look cute, but to make data legible. For example default is “sequential data” and schemes are optimized to show progress from low value to high value in clearly defined steps. So it will not offer opposite colors, but those that follow each other in intensity.
Click learn more in nature of your data section there to see description of different modes.