I've built a couple of finger joint (aka box joint, comb joint) jigs - one of the Woodgears.ca design (Matthias Wandel) and one of Stumpy Nubs (Jim Hamilton) design. My experience in doing that is written here. I made a few mods, though.
Here is the Woodgears jig:
and here is the Stumpy Nubs jig:
Thanks for looking!