Scrolling up or down in a web browser!
The easiest shortcut to scroll down without the mouse in a web browser is the space bar (tested in Safari, Firefox and Camino). One thing that always annoyed me about this shortcut is that I had to resort to the mouse to scroll back up. It is possible to modify it slightly however, and use it to scroll up. The shortcut is "Shift-Space Bar". The only problem about this shortcut is that if the cursor is currently in a text box, it won't work.