If you are having trouble understanding how to use PhoneGap/Cordova's config.xml file, or perhaps just want to see examples of what various options do, please check out Holly Schinsky's excellent new tool: Interactive Guide to PhoneGap config.xml.
Her tool lets you browse a config.xml file and see documentation on each and every major feature. Even better, she includes lots of screen shots and animations to give you a visual idea of what certain settings change.
p.s. Ok, this isn't new, but I don't see a lot of people talking about it so I figured it deserved some press. ;)