I remember when I was little I fell down the ladder for our village house with my Gameboy Advance in hand. The battery case broke off, but the system was still perfectly functional. I probably dropped it countless other times as well, not like I would remember.
As for my 3DS, the answer is twice. Both times involved the power cable, but it still functions. I'm actually rather paranoid about the mere thought of dropping it so I put a Wiimote wrist-trap on it in case my hands slip.