Graphical popup wiindow on link mouseover

Hi everyone, I have a link on a page and I would like to present dynamic list of names in graphical popup "window" ( and I use this term loosely) at the cursor position when a mouseover or the link is done. I don't want a "browser" window to popup but rather something like resembles a floating square or layer with a border perhaps. I've been doing some research and I am aware that you can use the title attribute of the <a href> tag, I'd like to do something a little bigger. Has anyone ever done this before? Thanks in advance, Jim