I've got some great information to pass on. One of our open source contributors Joa Ebert contributed some code to enable a very useful feature in FlexMojos 4.0. FlexMojos 4.0 will ship with a new feature for rapid application development and good old Flash experiments.
Continuous compilation monitors your source path and dependencies. Whenever your SWF needs to be recompiled FlexMojos will do so and launch a Flash Player showing the output file.
This is a great feature since it is independent from any IDE. A common scenario is a small Flash experiment. You might want to tweak parameters and play around with it. Thanks to FlexMojos you can omit the step of having to compile and launch it. Just type your code and get instant results.
You save precious time as well since the Flex compiler will stay in memory and the Java Virtual Machine does not need to be restarted.
To enable continous compilations for any application project you have to run the "cc" goal. You can also enable continous compilation for libraries using the "cc-swc" goal.