Its called an Air Hammer.
works...but not always & can get pretty messy pretty quick if you're not carefull.
Bring em out Chris....I'll give you a hand to get those out. Soak em in wd40 or liquid wrench first.
skip the wd-40...it wont do much as a penetrating fluid...it's main use is for water-displacement (wd).
like gerry said...try liquid wrench...or pb blaster or rost off (wurth product). a little heat might help too (carefull not to burn that sweet og mango paint) and a couple sharp and quick "shocks" from a punch & hammer might help "free" it up.
pretty sure that the tool chris is talking about is the one in the link below. last i heard steve w. (beetleman here on the asf) might have one for rent/barter/borrow...? it's something i'll need to use pretty soon to for the pins on the 64!
http://www.thesamba.com/vw/classifieds/detail.php?id=522556