I like jumping off rooftops and stabbing them in the neck in Assassins Creed 2 and Brotherhood.
Hell, I like that so much, sometimes I'll climb up on top of buildings, just so I can jump off and stab them. Even if it might have been easier to just run up and stab them.
Then again, I love pretty much all the cool little ways to kill people in Brotherhood. Poison, especially the darts, that's my favorite way to kill those snitch witnesses. Shoot em with the dart, saunter away slowly, grin when I lose all my notoriety.
And let's not forget the overpowered Crossobow. I once killed an entire room of enemies with that thing without ever getting noticed. I just shot and killed one guy, everyone else comes over to investigate, and I just pick them all off one by one.
Also, in Fallout New Vegas, I have a playstyle called the "John Wilkes Booth" in which I just sneak around shooting people in the back of the head with a revolver.