Is there a module that creates a jquery-like bar that displays system messages at the top of the page?
You could have a look at the "Purr Messages" module - I haven't used this myself, so I don't know if it allows for the messages being displayed at the top - it says it creates a "jquery popup," which I suppose means an absolutely positioned div which either fades out or you can click away with your mouse.

I did something similar to this this on one site by simply editing page.tpl.php - but it sounds like you want a module, &amp; not coding advice.