Spandex has exceptional elasticity. It is stronger and more durable than rubber. Apparently it was so-called because it is an anagram of 'expands' but that depends whether you believe the Americans.
Spandex is already used as apparel for sports such as wrestling, wetsuits, cycling and athletic garb, but also for compression garments such as surgical supports, and even in bra cups and superhero costumes.
It has also been suggested that wearing spandex can have a calming effect on some sufferers of autism.
Spandex is so popular in certain situations that it even has it's own brand of fetishism.