If you are developing pages specifically for the iPhone (since that appears to be the only way to create "applications"), you may find yourself wishing you had a better debugging tool than using alert() statements in your javascript. Well the good news is that such a tool already exists; a version of Firebug (already a popular debugging tool) has been created for the iPhone. It's a little convoluted since the Firebug server needs to run on a separate computer and the iPhone communicates with this server to display information, but it looks like it'll work and if you already use Firebug, there's not much new to learn here.