Not specifically e-related but tools I find indespensible include:
Fourmost miter cutter and sander (http://www.geocities.com/fourmost1/index.htm
Third the Dremel. I find I use the wimpy little Mini-Mite cordless one much more than the old powerful one on the cord.
Along with the Whattmeter, a decent tachometer is a plus.
Also, a good quality scale! Also a good quality covering iron like the Coverite 21st Century unit.
I'm sure there are more....