Efecto arcoiris en los links al pasar el cursor

Con un script vamos a dar un efecto de arcoiris al pasar el mouse sobre los links. Este efecto se aplica para todos los links que tengas en el blog.

Para poder integrarlo en vuestro blog, vamos a Plantilla, Editar HTML y buscamos </head>, antes pegamos esto:

<script>
//<![CDATA[
/************************************************************************/
/* Rainbow Links Version 1.03 (2003.9.20) */
/* Script updated by Dynamicdrive.com for IE6 */
/* Copyright (C) 1999-2001 TAKANASHI Mizuki */
/* takanasi@hamal.freemail.ne.jp */
/************************************************************************/
var rate = 20; // Increase amount(The degree of the transmutation)
if (document.getElementById)
window.onerror=new Function("return true")
var objActive; // The object which event occured in
var act = 0; // Flag during the action
var elmH = 0; // Hue
var elmS = 128; // Saturation
var elmV = 255; // Value
var clrOrg; // A color before the change
var TimerID; // Timer ID
if (document.all) {
document.onmouseover = doRainbowAnchor;
document.onmouseout = stopRainbowAnchor;
}
else if (document.getElementById) {
document.captureEvents(Event.MOUSEOVER | Event.MOUSEOUT);
document.onmouseover = Mozilla_doRainbowAnchor;
document.onmouseout = Mozilla_stopRainbowAnchor;
}
function doRainbow(obj){
if (act == 0) {
act = 1;
if (obj)
objActive = obj;
else
objActive = event.srcElement;
clrOrg = objActive.style.color;
TimerID = setInterval("ChangeColor()",100);
}
}
function stopRainbow(){
if (act) {
objActive.style.color = clrOrg;
clearInterval(TimerID);
act = 0;
}
}
function doRainbowAnchor(){
if (act == 0) {
var obj = event.srcElement;
while (obj.tagName != 'A' && obj.tagName != 'BODY') {
obj = obj.parentElement;
if (obj.tagName == 'A' || obj.tagName == 'BODY')
break;
}
if (obj.tagName == 'A' && obj.href != '') {
objActive = obj;
act = 1;
clrOrg = objActive.style.color;
TimerID = setInterval("ChangeColor()",100);
}
}
}
function stopRainbowAnchor(){
if (act) {
if (objActive.tagName == 'A') {
objActive.style.color = clrOrg;
clearInterval(TimerID);
act = 0;
}
}
}
function Mozilla_doRainbowAnchor(e){
if (act == 0) {
obj = e.target;
while (obj.nodeName != 'A' && obj.nodeName != 'BODY') {
obj = obj.parentNode;
if (obj.nodeName == 'A' || obj.nodeName == 'BODY')
break;
}
if (obj.nodeName == 'A' && obj.href != '') {
objActive = obj;
act = 1;
clrOrg = obj.style.color;
TimerID = setInterval("ChangeColor()",100);
}
}
}
function Mozilla_stopRainbowAnchor(e){
if (act) {
if (objActive.nodeName == 'A') {
objActive.style.color = clrOrg;
clearInterval(TimerID);
act = 0;
}
}}
function ChangeColor(){
objActive.style.color = makeColor();
}
function makeColor(){
if (elmS == 0) {
elmR = elmV; elmG = elmV; elmB = elmV;
}
else {
t1 = elmV;
t2 = (255 - elmS) * elmV / 255;
t3 = elmH % 60;
t3 = (t1 - t2) * t3 / 60;
if (elmH < 60) {
elmR = t1; elmB = t2; elmG = t2 + t3;
}
else if (elmH < 120) {
elmG = t1; elmB = t2; elmR = t1 - t3;
}
else if (elmH < 180) {
elmG = t1; elmR = t2; elmB = t2 + t3;
}
else if (elmH < 240) {
elmB = t1; elmR = t2; elmG = t1 - t3;
}
else if (elmH < 300) {
elmB = t1; elmG = t2; elmR = t2 + t3;
}
else if (elmH < 360) {
elmR = t1; elmG = t2; elmB = t1 - t3;
}
else {
elmR = 0; elmG = 0; elmB = 0;
}
}
elmR = Math.floor(elmR).toString(16);
elmG = Math.floor(elmG).toString(16);
elmB = Math.floor(elmB).toString(16);
if (elmR.length == 1) elmR = "0" + elmR;
if (elmG.length == 1) elmG = "0" + elmG;
if (elmB.length == 1) elmB = "0" + elmB;
elmH = elmH + rate;
if (elmH >= 360)
elmH = 0;
return '#' + elmR + elmG + elmB;
}
//]]>
</script>

Con ese script, podrás hacer que todos los links de tu blog tengan ese efecto, puedes ver mejor como funciona este efecto en este blog de pruebas.