Instructables user ivanjunge found a super easy way to fix the frayed and cracked ends of connector cables using a bit of PlastiDip, a paint-on rubber coating.
It is a bit better than slapping on some duct tape, and a whole lot better than buying new connector cables for your iPhone or other devices, as they can be pricy and there's no sense in throwing away the whole thing when just a part of it needs repair.
"I got my first can of PlastiDip the other day, knowing that I will find cool uses for it. I got a paper clip and gently painted the cracked portions of my iPhone cord with this stuff, overlapping some. It seems to dry completely in a couple hours."
Here's a quick video showing how flexible the cord still is with the PlastiDip coating -- practically like new:
Another option is to apply a bit of Sugru to the ends of cords where they're likely to fray in the first place, to help reinforce them. Of course, you can also apply a bit of Sugru after the damage has been done too. The difference between a repair with Sugru and PlastiDip is the flexibility of the cord after it's fixed, as Sugru dries hard.
Do you have other solutions to fixing cracked connector cables? Let us know!