Pushing zombies through the window
Throwing items through the window
Bottles = throwing bottles create sounds
Throw able items can destroy windows
Peeking before opening doors or use mirrors to peek
Zombie falling through stairs when pushed
Dismembering zombies when hit by a sharp weapons like axe
Bashing zombies while running
Different animations when destroying doors with different weapons
Jumping through different floor to the gr
Peeking is actually something that is planned as part of the animation update
While it may have changed a bit, here's an old sneak peek of the WIP system:
Since outside doors have windows now I don't see why you couldn't at least peek through them as well