The best weapon in your arsenal is a designer (human).
I built a theme using a palette from colorcombos.com, and thought it was just great. When I suggested the same colours to have a logo created, the designer I worked with tweaked them without even asking.
When I applied the new colour to the website, it knocked the wind out of me. Some people have the gift. There's no replacement for an artist who understands what you're trying to express.
She managed to change the way I feel about my own project.
Well, these are merely tools. Just like every tool, the user must be able to judge and finetune the output, and re-adjust when needed. At the very least, using such tools you won't be hurting anyones eyes. But you possibly won't be taking any awards either.
I agree. When human designers are not around, however, and I urgently need a 5-color diverging, colorblind safe, print friendly palette, I go to http://colorbrewer2.org/
If the original title begins with a number or number + gratuitous adjective, we'd appreciate it if you'd crop it. E.g. translate "10 Ways To Do X" to "How To Do X," and "14 Amazing Ys" to "Ys." Exception: when the number is meaningful, e.g. "The 5 Platonic Solids."
As a designed I really find this kind of tools useless. Especially when I get a color scheme delivered by the client.
It's not so much about that I'm an awesome designer (although I like to entertain that view of myself), but that five blocks of solid color says very little about how the colors will be used.
One problem is that the amount of colors you use and what elements get what color will completely change the impression of the design. A block of solid orange also can't express the subtle effect of gradients. Have a look at the spoon in this photo for an example: http://static.howstuffworks.com/gif/tea-8.jpg
Another problem is optical illusions. The perception of colors change very much with how much of them you see. A thin text will need to be darker that a bold headline to appear equal, and one color will look different next to two others (making a solid color look like a gradient next to an actual gradient).
The tool that would be useful would be an editor that lets you pick colors for specific stereotype elements of a website, like a h1-h3 header, body text/background, blockquote, logo etc, combined with font, textsize and boldness.
I'm not totally happy with any I've tried yet (they all have some glaring UI annoyances) but http://colorschemedesigner.com/ has been pretty useful for me.
All you need is some basic color theory and adobe kuler http://kuler.adobe.com/ which is a helpful tool, integrated into CS applications. This applies to all color related work. Kuler is the best option if you're using CS.
I built a theme using a palette from colorcombos.com, and thought it was just great. When I suggested the same colours to have a logo created, the designer I worked with tweaked them without even asking.
When I applied the new colour to the website, it knocked the wind out of me. Some people have the gift. There's no replacement for an artist who understands what you're trying to express.
She managed to change the way I feel about my own project.