Console killer apps

[amidar]

snes - street fighter 2
ps1 - silent hill (second ps1 sold the first)

[MikeRox]

Never used to buy my own consoles before the 128bit gen so I guess I can't really have any games that convinced me before then.

Dreamcast - Toy Commander (don't ask me why, it just looked so appealing with it's rich and vibrant settings, the different vehicle types you controlled as well, this game is the game thats impressed me more than any other on a console POD)

PS2 - Gran Turismo 3, literally the graphics were enough. :x

Xbox - Jet Set Radio Future, well, can't win them all :P

Gamecube - As fanboyish as it sounds, the Nintendo logo is pretty much all I needed to know I wanted one, jus all the fond memories of N64 multiplayer.