AS,
Your memory is probably right about the plane crash. Although I've not been able to locate the plaque either, I've got some friends who had gotten off the Calkins route a few winters ago and found the plane wreckage. I've also heard some eerie tales about seeing ghosts wearing summer clothes and sneakers near the summit in the dead of winter, and mysterious footprints in the snow that just end near the wreck. A highly respected professor was one of the eye witnesses who I first heard the story though.
BOOOOOOOOOOO!
As far as the pins go,
I know many peaks are not available,
Sounds like a good business or fund raising opportunity....