The first idea that popped into my head was having a picture of someone who was clearly timid in real life, followed by a picture of the same person playing taking charge and being ultra-sociable the minute they're plugged into an online game. Might be hard to capture in a couple of images though.
I spent 10 odd years playing Everquest, World of Warcraft etc, and nothing amazed me more than the transformation of some people once they were protected by a degree of anonymity and once the danger of having your head caved in for being an arse was removed.