One of these should be in everyone's AVR toolkit. Sad to see Microchip Atmel discontinue it. Such a useful piece...especially for unbricking misconfigured fuse settings that prevent ISP access. Most useful for production batch programming as well.
I just recently added the HV Parallel Programming header, the device pin header, and the 40 pin ZIF socket to mine. I had accidentally bricked a SOIC-20 ATtiny26, and with an SOIC adapter I was able to successfully rewrite the fuses with it, allowing ISP access once again.
Especially useful for presetting fuses and pre-flashing the Optiboot bootloader for devices being installed into an Arduino.
Wish I knew where to pick these up from on the used market. Would love to grab a few just to have on hand in case one fails.