I have seen people place plants on top of their monitors and computers. Dangerous, if you water the plant and the water trickled into the monitor or computer, just imagine what would happen. When you hear of a storm coming unplug everything from your computer including the telephone cable in the back of the modem, pull the power plug from the wall socket and dont use the computer until the storm has well past. SUN - Dont put your computer near a strong source of sunlight, say by a window. Apart from the sun's UV rays permenantly discolouring the computers casing it can also cause the computer to be working outside its safe working temperature and cause it to overheat.
Many people choose to put their computer system case directly onto a carpeted floor.
Over an extended time your computer will get clogged with dust much more quickly and could cause it to overheat. It is more ideal to put the computer case up off the floor on a normal table or computer workstation.