A friend was having problems with his GPS reciever. He figured out that the thing probably needed a "reset", but there was no reset button, and removing the battery had no effect. After a bit of sleuthing, he figured out that there was a "backup" battery which is why removing the battery did not cause a reset.
I liked his write-up of the process to bypass the backup battery to get the device to reset. This is a great example of why all electronics need a "reset" button. It's stupid that he had to go to these extremes just to reset the dang thing.