Brother label printers (and I assume others) can print text small enough and sharp enough to fit onto USB connectors. (You'll need to manually trim the label with scissors to fit of course)

Visually, if it's something I'm going to be staring at on a daily basis, I like this much better than having tags hanging off of the cable. Tip: consider white-on-black labels.

The labels have been plenty durable in my experience, but if you need extra durability, you could probably just brush some lacquer over it with a Q-tip.