As more people pour onto the web accessibility is important & ample contrast is essential for a variety of disabled users. Check the colors of your site with this free online color checker tool. It compares foreground & background color combinations of all DOM elements to determine if they provide sufficient contrast to meet W3C suggestions. This is handy, thanks Giovanni .
Get a color report on any website that includes color HEX codes, a chart of hue distribution, a color wheel & other websites with similar colors. They also have a small library of color reports for some of the large tech sites.