New from google...
The AJAX Libraries API is a content distribution network and loading architecture for the most popular open source JavaScript libraries. By using the google.load() method, your application has high speed, globaly available access to a growing list of the most popular JavaScript open source libraries.
http://code.google.com/apis/ajaxlibs/documentation/index.html#mootools
DropboxUploader -- Upload files to a Dropbox account.
DIG -- Dynamic Image Generator
gus -- Google URL Shortener
makeQR -- Uses google chart api to make QR codes.
MODxTweeter -- Update your twitter status on publish.