The most useful cables I've had in my laptop bag over the years are a 6" USB-Lightning cable, a 12" USB-microUSB cable, and (many years ago) a 4" USB-iphone(30pin) cable. None were particularly easy to find/obtain at the time, but while everyone else was sorting out tangled messes of 3' cables, I was up and running.

I welcome these. $8 each hits a price point where I won't even think twice about it as it's a convenience I'm happy to pay for.

If I might make a request -- a USB-miniUSB would be handy, especially for older but otherwise useful devices.