<style type="text/css">
/*<![CDATA[*/
#ontopbar{
    position:absolute;
    border: 1px solid black;
    padding: 10px;
    background-color: lightyellow;
    width: 100px;
    visibility: hidden;
    z-index: 100;
}
/*]]>*/
</style>

<script type="text/javascript">
//<![CDATA[

/***********************************************
* Floating Top Bar script- © Dynamic Drive (www.dynamicdrive.com)
* Sliding routine by Roy Whittle (http://www.javascript-fx.com/)
* This notice must stay intact for legal use.
* Visit http://www.dynamicdrive.com/ for full source code
***********************************************/

var persistclose=0              //set to 0 or 1. 1 means once the bar is manually closed, it will remain closed for browser session
var startX = 100                //set x offset of bar in pixels
var startY = 30                 //set y offset of bar in pixels
var verticalpos="frombottom"    //enter "fromtop" or "frombottom"
var barID="ontopbar"            //element ID


function iecompattest(){
return (document.compatMode && document.compatMode!="BackCompat")? document.documentElement : document.body
}

function get_cookie(Name) {
var search = Name + "="
var returnvalue = "";
if (document.cookie.length > 0) {
offset = document.cookie.indexOf(search)
if (offset != -1) {
offset += search.length
end = document.cookie.indexOf(";", offset);
if (end == -1) end = document.cookie.length;
returnvalue=unescape(document.cookie.substring(offset, end))
}
}
return returnvalue;
}

function closebar(){
if (persistclose)
document.cookie="remainclosed=1"
document.getElementById(barID).style.visibility="hidden"
}

function staticbar(){
        barheight=document.getElementById(barID).offsetHeight
        var ns = (navigator.appName.indexOf("Netscape") != -1) || window.opera;
        var d = document;
        function ml(id){
                var el=d.getElementById(id);
                if (!persistclose || persistclose && get_cookie("remainclosed")=="")
                el.style.visibility="visible"
                if(d.layers)el.style=el;
                el.sP=function(x,y){this.style.left=x+"px";this.style.top=y+"px";};
                el.x = startX;
                if (verticalpos=="fromtop")
                el.y = startY;
                else{
                el.y = ns ? pageYOffset + innerHeight : iecompattest().scrollTop + iecompattest().clientHeight;
                el.y -= startY;
                }
                return el;
        }
        window.stayTopLeft=function(){
                if (verticalpos=="fromtop"){
                var pY = ns ? pageYOffset : iecompattest().scrollTop;
                ftlObj.y += (pY + startY - ftlObj.y)/8;
                }
                else{
                var pY = ns ? pageYOffset + innerHeight - barheight: iecompattest().scrollTop + iecompattest().clientHeight - barheight;
                ftlObj.y += (pY - startY - ftlObj.y)/8;
                }
                ftlObj.sP(ftlObj.x, ftlObj.y);
                setTimeout("stayTopLeft()", 10);
        }
        ftlObj = ml(barID);
        stayTopLeft();
}

if (window.addEventListener)
window.addEventListener("load", staticbar, false)
else if (window.attachEvent)
window.attachEvent("onload", staticbar)
else if (document.getElementById)
window.onload=staticbar
//]]>
</script>

<div id="ontopbar">
    <a href="" onclick="closebar(); return false">[X]</a> Your content here.
</div>

<div id="ontopbar">
    Your content here.
</div>

http://www.dynamicdrive.com/dynamicindex17/floatbar.htm