Engine cleaner

I know I'm not the first to say this, but how awesome a parts cleaner is the dishwasher?! Greasy parts in, clean parts out! Every shop should have one. A heavy cycle with lots of detergent will clean up all but the most caked on grime.
Of course, for us married guys, this assumes the spouse is a team player of the highest order. Shameless bribes help, too, and you have to take care that you don't play that card too much. Once a season is about right. It also helps if her Dad (my father-in-law) pulled this kind of stuff back in the day.
Just watch for flash rust on anything iron based....

Seems like you'd have alot of fallout doing this (as far as oily junk in the drain). If you go to your local NG Armory that has an OMS shop (vehicle maintenance) you could offer to wash some humvees in exchange for using a steam pressure washer on your parts. Build some raporte doing that and you could probably get use of a parts cleaner and a sandblaster as well.