Cat5 (6,7,etc) cuts make for some very good breadboard cables; they're just the right size, colored, stiff, and much much better quality than the specific ones sold online. Unless one needs more colors or different sizes, they're just perfect. The ready made ones aren't single core and not ideal for breadboarding, still they're handy for other uses; A while ago I was about to throw away a long (15 meters or so) cat5 one that I swapped after it had been chewed by a dog, but rather cut the damaged part, stripped away the external insulation and saved each wire, and man, they're really good, from the copper used to the consistency of their insulation.