Built a storage system for the Post Hole digger based on something I saw on TractorByNet. Attaching this beast has been one of my least favorite things to do with my tractor - to the point that I would almost rather dig the holes by hand! Someone described attaching a PHD as trying to manhandle a 300 pound mousetrap and I agree. I was able to attach it to the tractor in 10 min or so with this system - this was a 30-40 min task for me in the past.
I added two posts to the cross members of my implement shed and then ran a beam from post to post. The beam is held in place with some 2x6 "ears" and a pair of 10 inch nails in oversized holes that pin the beam in place - this allows me to quickly remove the beam when I attach the PHD, and slide it back in when I stow it after use. (The beam looks like it is part of the rafters in the photo, but it is significantly lower.) All I do is back in, attach the side links, remove the top link and attach the PHD & PTO, lift the 3 point up, slide the beam out and go. Now it is both under cover and easier to hook up. The orange rachet straps keep it stable when stored and balancing on the beam. I store half the PTO shaft in the garage to keep it in good shape.