Ryan Boudreaux includes all the code snippets you'll need in this demo of how to create an image hover-preview effect using HTML, CSS, and JavaScript.

Output: The results of executing the CSS, HTML, and JavaScript entered into the sections of the page. Figure A shows jsFiddle loaded in Internet Explorer 9 with empty code panes.

A basic and properly structured HTML/CSS drop down menu can serve you just as well. In fact, it may make your site appear more responsive to not use animations and instantly display the menu instead.