Tooltip.js

Web site: http://tooltip.crtx.org/

License: MIT-style

Tooltip.js is an unobtrusive behavior-style library built on top of scriptaculous that adds simple ToolTips to Web sites. ToolTips can be added by using specially named CSS classes or by using a simple JavaScript API. Tooltip.js has fewer features than overLiB, but is much smaller if you are already using scriptaculous. However, if you're pulling in scriptaculous just for ToolTips, then it's the same size.