Many of you may know this, but here's goes...
Sure, you know that you can view a PDF file or a document by zooming in/out with the side buttons and scrolling up/down or slide left/right with your mini-joystick.
But do you know that you can scroll and slide with your FINGER? Try it. Zoom in on a page and simply press down on the screen and move (or flick) up/down/left/right, you'll see.
This can also be down with your pictures (through Picsel Viewer).
Nice!
This reminds me of the iPhone "Multi-Touch" feature.