These are the Eagle source files for the Avrrrinator, a Bus Pirate 3 to AVR ISP adapter. Instead of running a rats nest of wiring to the Bus Pirate for programming, these adapters break everything out into the standard 6-pin ISP connector available on many boards.
A cable connection is all that is required to begin programming your board using the Bus Pirate and avrdude.
Straight Bus Pirate to AVR breakout with 5v/3.3v selection. No logic level translation. Simple and works.
Revision B isn't a program-many-AVRs-at-once board*, but lets you connect more than one AVR for individual programming. This is great for prototyping and flipping different bits on two identical circuits (low power projects, debugging, etc).
The Eagle files are available for Rev B. Not much will change since this ended up being more of a toy/experimental project than anything else. It works though!
* Saying parallel would be confusing since old-school parallel port AVR programmers are out there (and with many likely still in use).