The Beautytips module provides ballon-help style tooltips for any page element by integrating the BeautyTips jQuery Tooltip plugin by Jeff Robbins with Drupal. It provides an API for adding custom beautytips as well as some built-in features. Admins can enable rollover balloon-help style tooltips for text fields within forms. It also supplies hover tips for Drupal help links and advanced help links.
Most importantly, it allows developers to add their own custom beautytips popups to their site without having to delve into jQuery.
Check out this cool informational video for info on how to use BeautyTips to enhance your Drupal views. Note: This video is using version 6.x-1.x and there have been some changes since then, so consult the documentation before using.