Gear wrenches and the cordless drill. I hardly go for the ratchet and socket when most time the gear wrench fits right in and usually better for space restraints.
I love my dremel and agree that cobalt drill bits are the only way to go but the tool that has saved me more times than I can remember is my vise grips. That's why I have several styles and sizes. Best thing since sliced bread.
Leatherman Tool...I used to be a technician/mill wright in a giant factory from the 1800s...couple hundred thousand sqaure feet laid out across 4 levels and a labyrinth of outbuildings. The maintenance shop and all of my tools were on the second floor at the far end of the complex. No matter how much crap I carried with me, I'd always be missing the one tool I needed and I'd have to drag ass half a mile back to the shop. I was so proud when I got that thing. My boss commented "Great, now you're going to round off and strip every nut, bolt, and screw in the factory because you're too lazy to get the right tool for the job". He was absolutely right...but I've used the hell out of that thing and it saved me countless hours and miles over the past 20 years. I still carry that same tool whenever I'm traveling by truck, motorcycle, or rickety old Jeep. It's rarely the "right" tool for the job, but it's been "good enough" for hundreds of jobs.
Dynabrade Dynafile II hand held belt sander. Handiest little sucker I have. I use it all the time, saves a lot of hand filing & grinding. http://www.abrasivesupply.com/Dynabrade_40320_Dynafile_II_Portable_Belt_Machine_p/40320.htm
i built myself a belt grinder 10 years ago, its a 3"x48" i used a 3"x5" boat trailer roller and a 3/4hp compressor motor, i turn that thing on 20 times a day.
Lots of tools have made my approach to building better and increased the quality of my work. For instance: -Die grinder with carbide burrs, and assorted abrasive discs -Step bits -Hand-held electric preacher shear. Nothing cuts metal easier or more precisely. On a larger scale: -Bridgeport vertical Mill -Miller Synchrowave 250. Switching from the old Union Carbide TIG we had at our shop to the Miller was like when I switched from a wood hockey stick to a composite. I was doing the same thing, except suddenly at a much higher level instantly.
1/2" and 9/16' racheting dog bone wrench. 4 1/2" angle grinder Dremmel (I've burned up the motors on 3 of them and hope to find a tougher one) Leatherman Tool (receiving a Leatherman tool has been a right of passage in our family)