I have a reasonable workflow for developing an iFrame app for Facebook. It's reasonable because I can test the app on localhost with a local Apache in any one of a myriad of IDEs that support HTML, CSS, and JavaScript (Visual Web Developer, NetBeans, Komodo, Aptana).
But what if I want to develop a non-iFrame app with FBML? Is there an IDE for developing Facebook apps "locally" without uploading my work over and over to Facebook?
For those doing Facebook app programming in FBML, have you come up with a system of working with reasonable turnaround?