Not that you could ever have enough websites to help you choose color schemes that actually match here is another one to add to the list!

Color Scheme Designer

I think that these sites are really helpful when choosing a color scheme and they keep getting better and better here is an updated list of a few of them

ColorCombos
COLOURlovers
ColorJack

UPDATED: Here are 25 more for my webhost:

1. 4096 Color Wheel
2. ColorExplorer
3. Color Combos
4. [ws] Color Scheme Generator 2
5. Color Wizard Ver. 3.0
6. colordb
7. Color Hunter
8. ColorSpire
9. Web 2.0 Colour Palette
10. colorjack
11. Accessibility Color Wheel
12. ColorToy 2.0
13. Sessions.edu
14. Colorbe.com
15. Color Palette Generator
16. Kuler
17. Cymbolism
18. COLOURlovers
19. 100 Random Colors
20. Color Tools
21. Pic2Color
22. Color Blender
23. colr.org
24. Color Schemer
25. GenoPal

Here are a list of my previous points on the same subject:

Color Mixers
Hex Code Color Generator
ColorLovers

Choose colors more easily

This website is great at helping you find out what the Hex value is of a certain color, comes in super handy when modifying CSS sheets and styles

Here are some great color combinations for websites Colorlovers.com