Another type of connector, one which is used extensively by the N-Trak group, is the Anderson Powerpole connectors.
http://www.andersonpower.com/products/singlepole-connectors.html
(sorry, couldn’t figure out how to make it clickable) [:$]
I like my Brother labelmakers. Not the cheapest thing you can use, but I think the advantages are worth the small cost. Unless you’re the only one who will ever need to read the labels, it’s easier for everyone if you print them. They stick to the wires easily by simply folding over and bending back to self-attach. Cost depends on the quality of the label used and there are lots of choices. There’s no need for a waterproof label under the layout on wiring (at least I hope not!), so use the cheap stuff to print them.
I recently upgraded to a much nicer one for the same as what the first cost me, $20. The real cost is in the labels, so always see how much a labelmaker will cost to feed before buying.
A good labelmaker won’t just let you label wiring. You can also use it up top on panels and indicators. The new labelmaker is quite versatile and makes nicer looking labels, so I replaced many of the older ones with new. I even used it for some temp signage on a few buildings when I didn’t want to bother with firing up Photoshop.
There have been some good comments about using a consistent wiring system consisting of various sizes, form-factors, and colors, etc to identify wiring and simplify trouble-shooting. I agree and that’s how my layout’s wired. Makes troubleshooting easy. However, this doesn’t mean you don’t need labels. The wiring system cues can substitute for many labels, but not all. Plus it’s always easier to read a label than trace a wire underneath the benchwork later on.
i use the plastic clips that comes with your bread loafs. they come in different sizes and colors so you can color coordinate them. just write down what the wire description is and clip them on.