Intersting ways elements are being used?

Question

Does anyone know interesting ways elements have been used or are being used?

Answer 1

Bismuth, which is a very weak radioactive metal, is used in Pepto-Bismol.

Arsenic and mercury compounds were used as anti-veneral disease medicines.

Helium is used with oxygen in undersea operations to prevent bends, but causes people to sound like Donald Duck.

Uranium salts used to be used in coloring glass.