Although you can press the power button to blank the screen, sometimes that is awkward to do with one hand. Screebl has extensive settings to control the range of angles, sensitivity to motion, and behavior under conditions such as docked. Once you set it up with your preferences, you can forget it. I have the screen timeout set to 15 sec., so when I lay the phone on a flat surface, I know the display will soon be off. If I want the screen to stay on without holding the phone, I just place it on someting at a slight angle. When I use the calculator, I override the screen timeout using Tasker (to be released June 2010) so I can use it lying flat on a desk or table.