Electric garage heaters?
Second, the water vapor... it's warm, all your steel tools are cold, when it touches the water condenses out on the steel and you end up with a big pile of rusty tools.
If you use them a little it or in a shop with say, a broken window it's not that bad, but after a while it starts to add up.
Electric tends to be more expensive and not heat up as fast, but I used one of these:
http://www.northerntool.com/webapp/w...5960_200325960
(FWIW, got it for $70some at lowes or HD) and built a box for it so it basically ends up being a mobile unit about the size and shape of a box fan. Usually, I leave it hanging on the wall in the garage, but sometimes if I might put it under the car if I want it to heat up the concrete a little before I'm going to spend some time lying under the car. In my 25x24x15' (tall ceilings) uninsulated (but shares a wall with the house) garage it will take the chill off in a few minutes, in 20-40 minutes with it set at a little past the 1 mark it gets up to 55* or so when it's 20-30 outside, which is a comfortable temp when working dressed normally for being in the shop.

If I had a bigger shop the solution that I like is to just get someone's old HVAC stack (air handler and heating coil) and a piece of the house ducting to direct the heat coming out the top of it across the shop. Stick it in a corner in the back of the shop, hook it up to a thermostat, and it will heat up the biggest shop in a couple of minutes and only cycle on every once in a while to keep the temp up.


