Haast's eagle was a species of giant eagle with a 8-9ft (2-3 meter) wingspan that went extinct in New Zealand around the year 1400. Like with a lot of island fauna (.i.e. dodo, elephant bird, moa) it's extinction was propogated by human settlers, Polynesians that hunted their primary prey—the moa—to extinction and probably hunted them as well.
Assuming we ever can viable DNA samples, I think it would be great for some scientists to clone or genetically reconstruct them alongside moas. They would definitely help reduce the deer and boar populations on the islands.
Besides...who wouldn't want to see a giant ass eagle flying through the skies of Middle Earth?