One of the things I've had a hard time with when starting a design (new site, poster, etc) is figuring out the colors. Trying to find a combination of colors that triggers inspiration. Well, I worked out a rather simple means of creating a color palette using Photoshop.
Image version (with PDF for purchase) available on my DeviantArt page.
We start with a new Photoshop document by press Ctrl+N (or Mac equivalent) and changing the document width to 100 pixels and the height to 20 pixels.
Select the Gradient Tool (G), then click on the Gradient Editor to select or create a new gradient.
Click and drag the Gradient Tool the entire length of the document. You should have something similar to the following image:
Select Mosaic from the Filter menu: then set Cell Size to 10 pixels and click OK.
And that's it! You're finished. You should have an image that looks like this (expanded to 800x80):
You can use the Eyedropper Tool to select your colors or you can repeat the steps, except make your document longer and thinner to create a horizontal bar.