The original Saw milked its simple premise for all it was worth. Two people, stuck in a room, faced with horrifying choices. But only if you're a regular person. For the completely insane? It's a walk in the park... and a terrifying ride for those around you who do have a moral centre and the desire to live.
The above clip by Nocturnal Emissions, a parody of, uh, "Saw 7", is a bit gory and should be considered NSFW, depending on the type of office you're in. It was shot on one of those fancy RED cameras, with special effects rendered in Adobe After Effects.
I guess next time, Jigsaw should do some psychological profiling before selecting his victims.