Anything in the Left4Dead series. Shooting a hunter mid pounce and he falls down a building, ninjaing the tank so that he attacks your friends as you make a run for the safe room.
Bad Company 2. I was playing Valparado online, we were attackers. All of my teammates had fought our way to the top of the light house. Most of my teammates were either snipers or medics, while I was an engineer. All I could do was use my rocket launchers to try and blow up covers so my teammates could snipe them. The medics revived us because we were also being sniped at. We turns out everyone on my squad was a medic. The other team had found out who were the medics and who was blowing up there cover so they killed all of my squad, so about seven snipers who were low on ammo and health were left on top of a lighthouse with a 200 ft drop and a 90% chance of being sniped in a parachute. So my teammates and re spawned next to a helicopter, we all jumped in, me manning the turret, we flew towards the lights house when a tracer tart hits right below me. I alerted my team who started screaming, we decide instead of flying and shooting down the enemy as a distraction for the rest of the team to parachute down, to parachute from the heli onto the lighthouse. Well at that moment they shoot the RPG and it hits our underside so we all instinctively jump out and successfully land on the light house suppling the others with ammo, health, and reviving the dead ones. But here is the cherry. The heli also lands with us with approx. 002 health and being the engineer was able to repair it. We then made rounds landing the heli close to the enemy territory and deploying teammates. That is what online play was made for. My Best gaming moment.