[extropy-chat] what other "X-prizes" have been started ?

[user]

During the peak of the x-prizes publicity curve, while it was being won
and people were flying, etc., I heard a bit of optimism about the role of
bounties in general and the prediction that other X-prizes would be
started to spur innovation and discovery ...

To what degree has this occurred ?  Anyone know of any other
"X-prizes" being offered ?