The XML Validator Online BETA is using the following components:

jQuery 1.3.2(http://jquery.com)
jQuery Form Plugin(http://malsup.com/jquery/form/)
dp.SyntaxHighlighter 1.4.1(http://code.google.com/p/syntaxhighlighter/)
XPath for jQuery(http://coderepos.org/share/wiki/JavaScript-XPath/bindings/jQuery)
Konami Command(http://blog.othree.net/log/2008/09/20/konami-command/)

Thanks Ajaxload(http://www.ajaxload.info/) for the good ajax-loading.gif generator.
Thanks Iconfinder(http://www.iconfinder.net/) for the convenient icon search interface.

Thanks Khodjaev Stanislav(http://www.icojoy.com/articles/44/) for error.png.
Thanks Everaldo(http://www.everaldo.com/) for fatal.png and success.png.
Thanks Liam McKay(http://wefunction.com/) for warning.png.