Technicolor Tools

ColorsWow. Steve at Slayeroffice.com has an amazing color palette generator based on the design technique of Andy Clark.

You enter a hex code value for a color, then another to mix it with, and out comes a beautiful png graphic of the color scheme. Extremely nice work, Steve. This is a great resource for brainstorming color schemes. I've used a number of other methods, but this one gets the prize.

colorwheel

UPDATE

Ok, so the color palette generator at wellstyled (shown) is even better.
I still recommend one extension of the techniques: take a scheme you like and use Photoshop to adjust the hue locally, and generate as many versions as you need (perhaps for clients or your boss). Then it's even easier to get ideas. If your'e a new web designer, that's a good enough reason on its own to downlo ad a trial of Photoshop, I think.