JavaScript

Get wp:Greasemonkey (here) so that you can have your browser be even more useful. You might even want to use Super Greasemonkey if you like using the awesome JQuery library. I'm hoping that Super Greasemonkey makes it into the official version, and that you can specify in your script which JQuery library to run (like Google's hosted JQuery scripts) making it easier to keep compatibility with the JQuery API version and also avoiding the need to bundle JQuery.

• MediaWiki/js talks about using JavaScript in MediaWiki
• User Scripts are JavaScripts that you insert into your web browser such as Greasemonkey scripts. Userscripts.org is the open source repository of Grease Monkey scripts.
• MediaWiki/Presentation describes methods to produce presentations from your wiki

JavaScript Libraries

JQuery is included with Drupal, and is also used in many other projects. In this slideshow, you can compare JQuery with Prototype

JavaScript Callbacks

A great explanation of what are Callbacks and how to use them: http://javascriptissexy.com/understand-javascript-callback-functions-and-use-them/

Application Programming Interface