In playing with my Arduino board, I've had occasion to "brick" it a few times. Not completely, because there is a low level programming header on the board where you can reprogram a new bootloader into the flash. I didn't have a cable to do that, but I borrowed one and it worked fine.

I decided I'd need a programming cable for myself, so for only a few dollars in parts, built a parallel port programming cable. Since the only computer I have with a parallel port is my desktop machine (which is actually under my desk), I used a rather long (2 metre) ribbon cable for the connection. This might have been a poor choice, because loading the 32 kB of flash memory took just under an hour! That's something on the order of 100 baud. Hopefully I can get it to go faster by shortening the cable, and hopefully a lot faster. It will just be more awkward due to where my parallel port is. But at least I have a way to unbrick my Arduino now.