There's a tool I don't own, however, I rented it from Autozone and definitely made my life easier.
http://www.autozone.com/loan-a-tools/pi ... 09523_0_0/One of my shocks was rusted to the lower mount and no amount of penetrating oil, heat, BFH, twisting, or miscellaneous violence could fully release it. Tried this tool, took me 15 minutes to accomplish what I couldn't in 10 hours.
If I did more roadie-type stuff out west I would probably just buy one and carry it with me.
On a sidenote, the one I got was probably on the 2nd or 3rd rental, so my guess is that not many people have a use for one of these, as opposed to the regular puller.