Limor from ladyada.net comes with another interesting idea. She made a testing jig for her PCBs. Using some spring-loaded pins (AKA pogos) from ebay and a Protoshield PCB, she made the jig where the PCBs to-be-tested will be connected to. The pogos are connected to an Arduino which in turn, will sense the PCB to-be-tested when it is pushed onto the pogos. Then, the Arduino will start the pre-defined test procedure, and a buzzer will sound the "everything is in order" sound!
This is a very interesting idea if you are planning to make a batch of PCBs, and you need to have them tested. Check out the worklog, follow this link.