There is another use of the cloning technique mentioned in my last post. According to the NYT article, the idea would be to inject elephant eggs with mammoth DNA, and over the generations breed a pure mammoth from pure elephants.
Well, if we can do that, what's to stop us, say, breeding more Yangtze river dolphins from all those bottlenoses we have in water parks? The Yantze dolphin has been declared functionally extinct, which means there's no longer a large enough population to allow them replenish their numbers. Just stick a few dozen of our home-grown cetaceans in there with them, and maybe they'd have a shot.
Actually, I acknowledge that the Yangtze dolphin probably isn't the best example, since even if it is functionally extinct as oppose to literally extinct (the last confirmed sighting was four years ago, apparently), we'll never make new ones in time. But there are three other river dolphin species, none of which are doing so hot right now, and hundreds of other mammalian species who are far, far closer to shuffling off this mortal coil than we'd like. Why regrow extinct animals when we can add to the breeding populations of the critically endangered. It seems to me that this would also navigate at least some of the thorny moral issues in all of this, since in effect all we're talking about is growing suitable sperm/wombs for the actual population to avail itself of.