I wanted to try setting up a debugger for PHP on my Kubuntu dev box. After struggling for a few hours with setting up the Zend Debugger on my LAMP server, I stumbled onto this page, which had me up and running in about 5 minutes:

http://techmania.wordpress.com/2008/07/02/debugging-php-in-eclipse-using-xdebug/

I can now step through my PHP, view variables, set breakpoints, etc, on my Kubuntu 9.04 machine. Wish I had tried that first over the Zend debugger.