The Google API Demo is back up with PHP source code. Just a simple example of a search page, with spellcheck. All that's required is the NuSOAP PHP/SOAP Toolkit and a Google Developer Key
If I ever get a free second, I want to whip up a desktop version using PHP-GTK
update - 2007-02-19 - The api demo still exists, but the working example on this site is now in Rails
Chris keyed this in on: 2004-08-30
Filed in: PHP, Rails, Web Development