I've mentioned SapphireSteel's Amethyst Visual Studio plugin-in previously. SapphireSteel has just announced the availability of Beta 5 which, among other things, adds refactoring support, improved debugging, and more. If you are a Visual Studio developer who also uses (or wants to use) Flex, this one is worth a look at.
Way too confusing and complex to set up. Let me know when they get down to a single easy install package. Might be worth it if you can't get or afford FB3 but I wouldn't know since I never got to use it, looks nice though.
best wishes
Huw