Learn how to load Arduino bootloader on a ATMEGA328 IC using ISP programmer and Arduino board. randofo @ instructables.com writes:
Bootloading an Arduino with a ZIF socket allows you to easily program a lot of chips at once without worrying about mangling the pins. The reason for this is that ZIF stands for “zero insertion force,” and as the name implies, ZIF sockets don’t require any force to take the chip in or out. This means that you do not have to worry about any of the pins bending when you take the chip in and out of the socket. This is particularly useful if you need to bootload a lot of Arduino chips at once for inclusion in an electronics kit or if you need to repeatedly program a chip and transfer it back and forth between a separate circuit board.
Bootload an Arduino with a ZIF Socket – [Link]