Theme Tweaker lets you fine-tune the colors in your theme with no CSS/PHP editing. It displays the existing colors from your current theme, and gives you a color picker to replace them. It also lets you change them in bulk, like invert all colors, use grey scale, sepia etc.
Once you are done, Theme Tweaker allows you to preview or activate your changes. If you are happy with your tweaks, you can save the modified stylesheet locally at the click of a button and upload it into your blog server to deploy your new color scheme.
Theme Tweaker can also generate a fully functional child theme for you! Using child themes, you leave your original (parent) theme untouched, so that it can be updated independently without losing your tweaks.
Finally, Theme Tweaker will remember your saved color schemes for any number of themes. Your tweaks are not lost when you switch themes.
Download link: http://wordpress.org/extend/plugins/theme-tweaker/
Plugin homepage: http://www.thulasidas.com/theme-tweaker
Recently updated to revamp the admin page interface with JavaScript tool tips hiding detailed instructions and comments, as well as to give new database cleanup options.