Checkmycolours.com spots color gaffes in your web designs
One more tool to consider adding to your arsenal is Checkmycolours. Drop a URL into the box and press the check button, and you'll receive an exhaustive analysis of page elements and their contrast ratio and brightness/color difference. You can view the complete report or switch to an error-only view to focus on potential problems.
No, an automated checker isn't a substitute for years of design experience and an eye for what works, but this can definitely be a helpful reference point.
Here's a shocker for you - Checkmycolours.com passes their own tests with flying...oh, never mind.
Want more great color tools? If you missed it, Dolores put together a fantastic roundup of 10 great online color apps.