I love running into the middle of a large group of enemies, intimidating them, and then activating Ninja Spy mode and jumping away. I laugh gleefully as I watch them milling about, swinging their swords ineffectually at empty air

Total "Batman disappears in a puff of smoke" thing. Awesome! If the graphics showed a puff of smoke, it would be even better.

Speaking of Batman - given that you now have easier access to the license, how about a bat-shaped shuriken?

Just a thought