The only trick I know of is to append an 's' to the end of the URL. Sometimes developers leave symlinks to their source code floating around. For example:
http://www.djskaven.com/tools/makethumb.php
vs
http://www.djskaven.com/tools/makethumb.phps
I keep the source accessible so that it's easy to "send" it to people. It's also just handy to have around while debugging, so you don't have to leave your browser to look at the code quickly.