Bill Gates wants to build a better condom.

He's offering a $100,000 prize.

[T]he foundation is calling for new shapes, materials and packaging that "significantly preserve or enhance pleasure, in order to improve uptake and regular use."

Trojan and Durex have been trying to do this for decades with ribs, contours and lubricants.

But "we know empirically that those don't work as claimed," the Gates Foundation's Stephen Ward recently told the Humanosphere blog. "The idea here is to seed innovative ideas."

Should this win?