I don't know how many of you use "re-purposed" or used lumber for the bus conversion, or for anything else for that matter, but I just thought I'd share what was just on "This Old House" on PBS.
It's called a de-nailing gun and goes by the brand name of Nail Kicker. What it does is shoots the nail from the back side of a board with a pneumatic piston, kind of like a nail gun in reverse.
Here's the website I found for it: http://www.reconnx.com/demonstration.html
I remember my days as a kid when dad would haul a bunch of salvaged lumber home, (He had a side business for a while tearing buildings down). My job would be to straighten up and pull all the nails in all the boards and do as little damage as possible. I got paid a penny per board, but if I damaged the board, it cost me a nickel. Dad made money on that deal.
This gun would have been a lot easier on my 6 or 7 year old fingers.
As a side note, I got a bright idea to use an pneumatic pop riveter to pull nails with a few years ago. It works good on most finish nails, but you need to tap the framing nails out a bit and nip the heads off first.