I started aggregating a bunch of useful sites to look for GFD informations on the web, some kind of specialized Google search engine.
You can find its homepage here:
If you want to insert it on your webpage, visit this page, or if you want to add it to your Google home page click on this button:
this page (which will reveal the engine parameters) and simply try to change the search engine on your Firefox Search toolbar, you should see an Add "GFD Search" line, click on it and you're all set !
The xml file is here.