I use my regular hand tools, power tools and welding/fabricating equipment all the time and really love all of them. The "favorite" ones that come to mind for me are not used every day but are absolutely irreplaceable when they are needed. Homefries already mentioned having one...
My "hot knife" tire groovers are worth their weight in gold and didn't cost much back when I bought them. I've had mine for about 15 years and used them when I was dirt tracking but never would've imagined how well they work for 4wd type use. With the right selection of blades you can cut, trim, groove and sype most any tire to improve its performance on varying terrains.
