AJAX Libraries API - Google Code

http://code.google.com/apis/ajaxlibs/

From the site:

The AJAX Libraries API is a content distribution network and loading architecture for the most popular open source JavaScript libraries. By using the Google AJAX API Loader’s google.load() method, your application has high speed, globaly available access to a growing list of the most popular JavaScript open source libraries including:

• jQuery
• jQuery UI
• prototype
• script.aculo.us
• MooTools
• dojo