Is there any 'FindBugs like' plugin for Adobe Flex Builder or Flash Builder
The only things I know that could be close to what you're looking for are external tools that you plug into your flex project.
MonsterDebugger is very complete debug console : http://demonsterdebugger.com/
MidnightCoders RIAappuncher is a great tool for monitoring RIAs bugs : http://www.themidnightcoders.com/products/ria-apppuncher/overview.html