I torque every drivetrain and chassis bolt to spec. I have many different torque wrenches in my tool box. It is also important to have the torque wrench calibrated periodically to insure accuracy. For critical engine fasteners like the headbolts and rod bolts, I use the torque angle method or stretch gauge with a dial indicator which is much more accurate than a digital torque wrench. ARP bolts has a good tech article on why each of these tension methods are better or worse than the others.
http://www.arp-bolts.com/pages/tech/fastener.html
I don't do the "feel" torque because after replacing your 2000th broken stud or bolt especially the M6 or M8 bolts in the car because someone before you had an "off day" or several people did, then you start to torque more fasteners as a regular practice. I always torque suspension fasteners because if one of those pieces fails it could mean an accident or worse. The wheels are an ALWAYS torque item because not only is it a way to double check your work but it saves the rotors from warpage because of uneven preload from the different torque values on each lugnut.
It maybe "overkill" to some but it makes for a safer more reliable vehicle after it leaves the shop because the job was done properly.
An extension on either side changes the torque values. Like the extension on a torque wrench multiplies the torque because the leverage changes. The correct torque measurement is going to be with your hand on the hand grip. The torque measurement changes when a socket extension is used as well but it is decreased. Also no reliable torque value can be obtained with a u-joint because the fulcrum angles change thus it is no longer measuring with any physical constant.
Troy
....Otherwise, I tend to do everything else (outside the engine) by feel. Feel can get you in trouble too though, especially with bolts that have been heat stressed, like exhaust manifold bolts. They tend to break rather easily if reused or even slightly over tightened. Same thing with bolts smaller than 10 mm. And like Ish said, you don't really want to mess around on an aluminum block. Some places are impossible to fit a torque wrench into, so I usually limit the torque I can put on a small bolt by using a "shorty" wrench, or even 1/4 drive on the really small stuff.
