So, the only thing that SHOULD be appearing during hover is the TITLE text for an image (if it's there)?
One reason we don't put anything of actual value in title attributes, as mentioned, is because tooltips are limited to mouse users (sometimes screen readers, in some situations and some settings, depends).
If you are forced to have things like icons, this is one area where too many users need the title to know what the icon/button/whatever does. This means the design is poor and there should be text explaining what the icon means, but if you are stuck in a situation where you cannot add real text and the icons are beyond silly, you can have the titles on the focusable element (usually icons are for things like links and buttons, so there are usually anchors or inputs in them, both of which are always natively focusable by keyboard) and use CSS to display the title as a tooltip for keyboard users.
It's not ideal and doesn't work in IE6 or 7 but it can be better than nothing in a bad design.