Inverts browser colors. I've in-lined a stripped-down version of rgbcolor.js and minified the entire script. For reference, checkout http://stackoverflow.com/a/4766232/435460

invert_colors_bookmark.js

javascript:var c=[{r:/^rgb\((\d{1,3}),\s*(\d{1,3}),\s*(\d{1,3})\)$/,p:function(b){return[parseInt(b[1]),parseInt(b[2]),parseInt(b[3])]}},{r:/^(\w{2})(\w{2})(\w{2})$/,p:function(b){return[parseInt(b[1],16),parseInt(b[2],16),parseInt(b[3],16)]}},{r:/^(\w{1})(\w{1})(\w{1})$/,p:function(b){return[parseInt(b[1]+b[1],16),parseInt(b[2]+b[2],16),parseInt(b[3]+b[3],16)]}}];function w(b){this.ok=!1;"#"==b.charAt(0)&&(b=b.substr(1,6));b=b.replace(/ /g,"").toLowerCase();for(a=0;a<c.length;a++){var d=c[a].r.exec(b);d&&(z=c[a].p(d),this.r=z[0],this.g=z[1],this.b=z[2],this.ok=!0)}this.r=0>this.r||isNaN(this.r)?0:255<this.r?255:this.r;this.g=0>this.g||isNaN(this.g)?0:255<this.g?255:this.g;this.b=0>this.b||isNaN(this.b)?0:255<this.b?255:this.b}function y(){var b=["color","background-color"];$($("*").get().reverse()).each(function(){var d=null,e;for(e in b)e=b[e],$(this).css(e)&&(d=new w($(this).css(e)),d.ok&&$(this).css(e,"rgb("+(255-d.r)+","+(255-d.g)+","+(255-d.b)+")"))})}function z(b,d){var e=document.createElement("script");e.src=b;e.onload=d;document.getElementsByTagName("head")[0].appendChild(e)}window.jQuery?y():z("https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js",y);