The Nintendo DS Opera web browser is set to land on European soil October 6th. In case you don't remember, the browser used the WiFi connection in the DS to connect to the internet, and both screens to render pages. There's a special mode in the browser where the top screen shows a zoomed in version of the selected portion of the bottom screen. Very nice implementation for the DS. The only problem is that the performance is a little sluggish, rendering pages in minutes instead of seconds.
Take a look at the video review to see how well it performs.