Using prototype.js v1.4.0
Prototype.js is a very useful javascript library for doing "Web 2.0" stuff such as AJAX requests and minor DOM manipulation. It just makes life easier by removing some of the redundant stuff that Web 2.0 projects always seem to involve. However, it's documentation sucks. This webpage, by Sergio Pereira, is a fantastic resource for anybody using prototype.js.
http://www.sergiopereira.com/articles/prototype.js.html