I'm sure I must have said this before, maybe to your alter ego, but if you use Win32::IE::Mechanize instead of WWW::Mechanize, the former is based on the MSIE core and it will process Javascript before handling the result to you. The disadvantage is that it'll only work on Windows.

There's also Selenium (in combination with WWW::Selenium, WWW::Selenium::Utils, Test::WWW::Selenium, etc.). Drives the browser using JavaScript, so works on several different platforms.

There's also wtr which is written in Ruby and, like Win32::IE::Mechanize drives MSIE directly. IMO it has a nicer API - but opinions may vary ;-)