Question

I would like to make information boxes like this one:

http://mmarfil.com/
[mouseover to see]

Answer 1

That particular site uses jQuery fadeIn and fadeOut to show an image (an actual png) of the tooltip like this:

$('.toggle').hover(
        function(){
            $('#baloon').fadeIn('normal');
        }, function() {
            $('#baloon').fadeOut('normal');
});

The image is positioned above the box using the css fixed positioning:

position: fixed;
margin-left: X px;
margin-top: Y px;

Similar results can be achieved using html, positioning a div instead of an image.