I found a usefull option on the iPhone 4G.
In fact, you can inverse all color of the screen, so you can see your films, your photos, play to your favorite games in negative effect.
For example, this is the screen with the button and the effect :
I hope someone will help me to find it, if this option exists.
And if it does not exist, i hope someone can create it, with for exemple a name like HD2 Negativ Color.