The jQuery Form Plugin allows you to easily and unobtrusively upgrade HTML forms to use AJAX. The main methods, ajaxForm and ajaxSubmit, gather information from the form element to determine how to manage the submit process. Both of these methods support numerous options which allows you to have full control over how the data is submitted.
qTip2 is the second generation of the advanced qTip plugin for the ever popular jQuery framework.
qTip2 provides you with tonnes of features like speech bubble tips and imagemap support, and best of all... it's completely free under the MIT/GPLv2 licenses!