The Sloth Bear (Melursus ursinus) is quite unusual, indeed; up until two years ago I had never even heard of this nocturnal bear from India, Nepal, and Sri Lanka. It is a bit mysterious why this bear is called the "Sloth Bear," however, although it does resemble anteaters (another member of the Xenarthra) in some of its habits. Sloth Bears do eat a variety of foods including meat and fruit, but some of their primary food sources are social insect nests like those of bees and termites, this bear sometimes being known as the "honey bear" because of its affinity for the sticky stuff. These bears aren't as friendly as Winnie the Pooh, though, and they can be quite vicious when confronted, although they are in far more danger from humans who want to harvest their gall bladders.
Yeah, the tropical Asian bear species tend to get somewhat overlooked. =)
I've heard various reasons for the name: one is that early European explorers saw the ungainly appearance and long claws and thought they were bear-like sloths (!). Other reasons I've read about from various anecdotal sources include claims that these bears were sometimes seen hanging from branches upside-down (those must have been some pretty small bears, or pretty huge branches!), or that the shambling shuffling gait is supposedly reminiscent of a sloth's. Whatever the case, it probably shows that the people who christened such a name probably knew much less about sloths or bears than they thought they knew. =D
Oh, and to add on, interestingly enough, the sun bear is also sometimes known as the "honey bear". And I find it intriguing that the sloth bear, sun bear and Asiatic black bear all share the trait of being black with a white marking on the chest.
As for threats facing the sloth bear, there's not just the awful demand for bear bile, but there's also the exploitation of sloth bears as 'dancing bears' and in the deplorable sport of bear-baiting.
Hai-Ren: You're right. The sloth bear was actually first described as a sloth (Bradypus ursinus) by Shaw in 1791. Same guy who also first described the platypus, kiwi, and budgie.