Sorry for the pun, I couldn't help myself.
The Wii is a global success, despite its curious name. Nintendo realised that they couldn't and shouldn't try to take Xbox 360 and Sony's Playstation 3 on head to head. Instead they have come up with a new way to interact with games - appealing to a softer breed of gamers. The success is commented on by Seth Godin here.
It's also a fine example of a product that has inspired users to create their own content. Not just the usual YouTube videos (this from Three Minds shows Wii being used in a cinema), but also Flickr groups, the really quite odd wiikitty website and the highly entertaining sites which show damage caused by wii-abuse - wiihaveaproblem and wiidamage (plus here's a T-shirt on a similar subject!).
An effect that I think will have come as a bit of a surprise is the beneficial effect on health. Several colleagues came back to work after Christmas complaining of stiff muscles from Wii gaming. This page describes how a guy monitored his loss of weight and body fat entirely due to Wii-ing. (Thanks to Three Minds for the link).
Create a remarkable product...