iPhone simulator on iPad

When using an iPad if you download and use an iphone application, an iphone outline will appear on the screen with the application inside.

I'm looking for a way to switch between viewing websites normally as they would appear on the iPad and iphone view.

What would be the best way of going about this?

Download an iPad browser, such as Dolphin Browser or Opera Mini.
Then download a web browser that is iPhone/iPod touch only, such as Mango Browser, iFox FREE, Sphere, or Full Screen Web Browser (99¢). Then you can run an iPad browser in the full iPad mode and run another browser that is in the 1x 2x iPhone mode.