New Scientist has a primer on extinct animals that might be candidates for resurrection by cloning. My preference is the short-faced bear:
This towering beast would dwarf the world's largest living land carnivore, the polar bear. The short-faced bear may have been a third taller than the polar bear when standing upright, and it weighed up to a tonne. Recovering its DNA should be possible as there are specimens encased in permafrost. The short-faced's closest living relative is the spectacled bear of South America. The two species parted evolutionary company only around 5 million years ago, but unfortunately, at just a tenth the body mass of the short-faced bear, the spectacled bear is unlikely to be a particularly good surrogate.
Or, OH OH, the giant beaver:
There is fierce controversy over the reintroduction of normal beavers in some countries, so imagine how much fuss there would be over the reintroduction of the 2.5-metre-long giant beaver to North America. It's not too much to hope for a genome sequence of this massive rodent, says Hendrik Poinar, a geneticist at McMaster University in Hamilton, Canada. The capybara, which is about half the mass, would probably be the most suitable surrogate, though it might still be too distant a relative.
It’s too bad Paleocaster is too old – their spiral burrows (“devil’s corkscrews”) are totally cool.
The article ends on the depressing note that the first resurrected species will likely be one that is now living – gorillas are the example mentioned. Since the cloning of the gaur, that scenario seems pretty likely.