A few of my favorite links from SassConf.
CSS Spinners (a cute site!) http://css-spinners.com/#/spinners/
True library https://github.com/ericam/true (ZOMG TESTING)
Our eyes are biased re: light and dark colors. However, there is a Compass plugin that will help you with that: https://github.com/timhettler/compass-yiq-color-contrast; and compass is going to use YIQ in the future to determine “light” and “dark” colors.
The new sassy website! sass-lang.com