Let's see...
In Saint's Row 2 I like to throw old ladies at oncoming vehicles. Also, in the Ultor stronghold mission where you have to assassinate the Ultor execs in the shopping mall, I killed the guards around one, dragged him to the next target, used him as a human shield to kill the second batch of guards, walked up to the cowering exec, executed his fellow in front of him, then grabbed the second exec and threw him through a giant sheet of glass that said "Ultor" in big letters. Also, I don't know if this counts, but the ending to the "Bank Error in Your Favor" mission deserves at least some mention.
In Fallout 3 I like to kill all the mercenaries who want my head for the bounty, then strip them of their equipment, line them up next to each other, cut their heads off and put their severed heads, facedown, over their own crotches.
In CoD WaW, I elected to have the trapped Germans killed by Molotov cocktail barrage instead of by bullets.
In Splinter Cell levels where I'm allowed to kill guards, I like to knock the first guard out, then kill all the other guards and pile all of the dead guards on top of the unconscious one. That way, when he wakes up, he's covered in dead bodies.