Simple jQuery module for fixing contrast according to W3 formula: http://www.w3.org/TR/AERT#color-contrast

gistfile1.js

if(jQuery) (function($) {
    $.extend($.fn, {
        fixContrast: function() {
            $(this).each(function(element){
                var backgroundcolor = $(this).css('background-color');
                var rgb = backgroundcolor.replace("rgb(", "").replace(")", "").split(", ");

                var ratio = Math.round((
                    (parseInt(rgb[0]) * 299) +
                    (parseInt(rgb[1]) * 587) +
                    (parseInt(rgb[2]) * 114)
                ) /1000);
                if(ratio > 125) {
                    $(this).css('color', 'white');
                }else{
                    $(this).css('color', 'black');
                }
            });
        }
    });
});