Superglue Accelerator (not a use, but a neccessity)
Accelerator is invaluable when working with superglue. Normally, if you use much more than a drop of glue, it takes forever to harden. With accelerator, you flood the area with superglue, hose it down with accelerator, and POOF! it's hard.
Note: Too much accelerator will turn the glue into strange, popcorn-looking gook with very few desirable qualities. Some practice will be neccessary to get a feel for the right amount. My advice: practice on scrap wood, rather than customers' guitars.

Filling dings in finishes
Forget lacquer, forget polyurethane. Who wants to wait hours or days for a finish patch to dry? This is the twentieth century! For small dings, all you need is superglue, a sharp chisel (for gross levelling), some accelerator (available at Stewart-MacDonald's) and a sanding block. Drop in slightly more superglue than you need to fill the ding, squirt with accelerator, and chisel off the lump(s). Gently sand with 600 wet-or-dry paper on a block, rub out with rubbing compound, and Viola! A nearly invisible patch.

Note: Do not use a buffing wheel on a superglue patch. The surrounding finish will sink, the superglue won't, and you'll have a noticeably raised lump.

Glueing hairline cracks
We've all seen those cracks -- in acoustic bridges and elsewhere -- that are too small to work wood glue or hide glue into. The solution: flood the area with superglue, get out your sanding block, and start sanding the puddle! The heat generated will harden the glue faster, the sanding dust will mix with the glue and fill the crack, and the area will be level when you're done. This procedure actually produces better results than you'd think. Note: Get the sanding block out of the glue immediately.

Fixing stripped screw holes
The quickest and easiest way I've found to fix a stripped hole (assuming the fit is still close) is to remove the screw, run a couple drops of superglue into the hole, and squirt it with the traditional accelerator. The screw should now grip nicely. If the hole is grossly oversized, you'll have to
• Drill it out to your nearest dowel size (hopefully, this won't be 3/4"), blop a little superglue gel in the hole, and pound in the dowel & level it off.
            OR
• Get a bigger screw.

Like so many other repair decisions, this one depends largely on how you feel about that particular customer. Decent guy = glue & dowel. Whiny jerk = bigger screw. Don't feel like you have to do your absolute best every single minute (see The Repair Guy Philosophy).