Ever wish you had another hand?
Granted, literally having another hand would make buying shirts more difficult - but when working on bicycle brakes and cables, there are a couple of ways to get that extra hand when you need it.
Let's take a look at some bike tools with a very "handy" name: 3rd-hand, and 4th-hand tools.
A 3rd-hand tool is used when working on most types of rim brakes, whether sidepull, centerpull, or cantilevers. In use, it holds the brakes closed, with brake pads close to the rim while you tighten the cable fixing bolt.
The way a 4th-hand tool works is that it acts like pliers with double-hinged jaws. One part of the jaws grabs hold of the end of the cable, while the other side of the tool butts up against the component (whether brakes or a derailleur). As you squeeze the handles, the jaws spread apart, pulling the slack out of the cable. Then with your free hand you can tighten the pinch bolt.
Some say that when working on brakes with a 4th-hand tool, you don't need a 3rd-hand tool, because while the 4th-hand pulls the cable tight, it can also squeeze the brakes to the rim. That may be true, but I still like having both. I especially find that, when working on either cantilever or centerpull brakes - with their straddle cables and yokes, etc. - having both tools works nicely with very little cable adjustment needed afterwards.
And besides - there are very few bike-specific tools where somebody doesn't eventually make the argument "you don't really need (fill in the blank)" and I tire of those discussions pretty quickly. If you follow that one to its logical end, eventually you arrive at "I've got some vise-grips and a hammer - and I can fix anything."
Check back from time to time, and I'll highlight some other fun items in the toolbox.