damn good air compressor, a lock to keep all the relatives from "borrowing" your tools, sheetmetal hand shear( or a beverly if $ permits), guess it depends on what you will ultimately be doin
My most coveted tool is an engine hoist/shop crane. It sure takes the "Back" out of working on my truck. Definately if you work solo. That and a short 4x4 piece of wood. I have 4 of them on hand and I use them all the time for different stuff.
I dont know what I would have done with out a vise. Mine has saved more time then any other tool I own. In that same note a couple of 3-4ft clamps are very nice to have around to