Simple but cross-browser library.

Applies SVG (using Keith Wood plugin for jQuery) or canvas method if supported on the client browser (includes explorercanvas patch for ie). If not, applies methods derivated from the work of Walter Zorn for compatibility.

The jQuery Project manages all of the jQuery projects, including jQuery Core, jQuery UI, Sizzle and QUnit.

TopUp is an easy to use Javascript library for unobtrusively displaying images and webpages in a Web 2.0 approach of popups. The library is jQuery and jQuery UI driven in order to maintain cross-browser compatibility and compactness.

The main goal of this framework is to provide a solid base for all of your front-end projects. It will help you go through the initial steps of creating a master template quickly, without having to worry about browser rendering issues for certain elements, including numerous JavaScript plugins to perform simple tasks or even worry about CSS naming conventions.

jQuery Tools is a collection of the most important user-interface components for today’s websites. This single JavaScript file weighs only 5.59 Kb

Rick Strahl has posted an excellent article that introduces jQuery, and walks-through how to take advantage of it within ASP.NET pages.