Map with pop-ups/javascript

We have a map on the site we\'re working on and we need help with making text appear when you roll the mouse over a location. For example, if you roll your mouse over the spot on South Africa, a small descriptio should appear. Preferably not a pop-up window as that would be blocked if people have pop-ups turned off. Something a bit more classy. No links in the info - just plain text at this stage.