<select name="cars">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="fiat" selected="selected">Fiat</option>
  <option value="audi">Audi</option>
</select>

* pegTo fn port from prototype.js */
$.pegTo = function(src,targ,opt) {
    opt = $.extend({
      setLeft:    true,
      setTop:     true,
      setWidth:   true,
      setHeight:  true,
      offsetTop:  0,
      offsetLeft: 0
    }, opt);
    var source;
    if(typeof(src) == "string") {
        source = $("#"+src)[0];
    } else {
        source = src;
    }
    var p = Ppage(source);
    // find coord sys
    var target;
    if(typeof(targ) == "string") {
        target = $("#"+targ)[0];
    } else {
        target = targ;
    }
    var delta = [0, 0];
    var parent = null;
    // delta [0,0] ok 4 position:fixed, position:absolute needs offsetParent deltas
    if ($(target).css('position') == 'absolute')
    {
      parent = PoffsetParent(target);
      delta = Ppage(parent);
    }
    // correct by body offsets (4 Safari)
    if (parent == document.body) {
      delta[0] -= document.body.offsetLeft;
      delta[1] -= document.body.offsetTop;
    }
    if(opt.setLeft)   target.style.left  = (p[0] - delta[0] + opt.offsetLeft) + 'px';
    if(opt.setTop)    target.style.top   = (p[1] - delta[1] + opt.offsetTop) + 'px';
    if(opt.setWidth)  target.style.width = source.offsetWidth + 'px';
    if(opt.setHeight) target.style.height = source.offsetHeight + 'px';
};
function Ppage(fel){
    var valueT = 0, valueL = 0;
    var el = fel;
    do {
       valueT += el.offsetTop  || 0;
       valueL += el.offsetLeft || 0;
       // Safari
       if (el.offsetParent==document.body) {
           if ($(el).css('position')=='absolute') break;
       }
 
    } while (el = el.offsetParent);
 
    el = fel;
    do {
       if (!window.opera || el.tagName=='BODY') {
       valueT -= el.scrollTop  || 0;
       valueL -= el.scrollLeft || 0;
       }
    } while (el = el.parentNode);
    return [valueL, valueT];
};
function PoffsetParent(el)
{
    if (el.offsetParent) return el.offsetParent;
    if (el == document.body) return el;
 
    while ((el = el.parentNode) && el != document.body) {
        if ($(el).css('position') != 'static') return el;
    }
    return document.body;
};

<select name="sel" size="2">
  <option value="one">1</option>
  <option value="two">2</option>
  <option value="three">3</option>
  <option value="four">4</option>
  <option value="five">5</option>
  <option value="siz">6</option>
</select>