SimPholders gives developers quick access to apps under development, as well as to simulators for iDevices.
With FUSE for OS X
When you install FUSE (osxfuse.github.io), SimPholders mounts a virtual file system where you can browse your simulators and apps like it should have been implemented by Apple. When you select an app you can see the app bundle, sandbox, and app group containers at a glance. When you enable the Finder Sync Extension there is even some functionallity in the context menus where you can perform all of SimPholders's actions.