AGLETS
These have to be the most widely used invention of all time. Every form of cord, string, rope etc, that is intended to go through an eye of any discription has been equipped with one of these to make the job of insertion so much easier. They also stop fraying, as anyone who has had a shoelace snap on them will be all too aware. Never before has an invention been so simple, yet so effective. I'm not sure that there is a patent on Aglets themselves, however there are patents on variations of them, and considering the simple genius of the Aglets themselves - this is a feat of it's own.
Submitted by: Tony Everett