I'm a N-head to the core, but I have to admit that Sony has contributed a lot to the industry. As Wellington, and a few others have said, they have driven the industry into the mainstream eye. To be sure, this was bound to happen eventually, but Sony has a huge hand in delivering it with a spoonful of sugar. Their keen eye for marketing has rocketed videogaming into the limelight in a way Nintendo and Sega could only dream of (that is, into the eye of not only kids, but teens and adults as well).
On top of that, they delivered Eye toy, and singstar, the kinds of games I would;ve expected the Nintendo of old to have delivered.
Oh yeah, Gran Turismo for the mainstream factor and Ico for the 'elite' gamer. And they gave me my first delve into DVD viewing. In fact, I'm still using my PS2, despite it's supposed crappiness as a player.