Stapler.

Whoever invented the Stapler really deserves some appreciation. Who would ever think to bind pieces of paper together with tiny strips of metal?

A quick check of Wikipedia informs us that the stapler was in fact invented by George W. McGill. He snagged the patent in 1866. Apparently the idea of fastening piles of paper with metals was in use before this though, even way back in the 18th century by the French royal court for royal papers.

Staplers are great.