I was looking up something on Google maps, and I used the mouse scroll wheel to scroll down the page. Except this time, it zoomed in on the map in realtime! And the developers even implemented it correctly, by zooming in on the current mouse pointer, not toward the center of the screen. The last program that I used that did this well was DeluxePaint, back in 1986; there are a few others that implement it, but they tend to be subtly broken. 3D modeling programs also tend to have this, but zooming in 3 dimensions is a bit trickier to predict.