I had a single page of "deep-sea facts" for many years on my website and always intended to update it, but procrastinated until just last night. Probably not much new to wtf_nature, though I couldn't find much mention of the Xenophyophores here.
http://www.bogleech.com/bio-deep.html - an intro to the Abyss and Ceratoid Anglers.
http://www.bogleech.com/bio-deep2.html - trivia page with various other fish.
http://www.bogleech.com/bio-deepjelly.html - ctenophores and cnidarians (including the siphonophores that have already been posted here)
http://www.bogleech.com/bio-deepcrust.html - arthropoda (possibly the shortest and least interesting. I'd have included Phronima, but that's already in my other Crustaceans article)
http://www.bogleech.com/bio-deepinverts.html - quick run-down of some other abyssal invertebrates, including Xenophyophora.
http://bogleech.com/bio-cart.html - finally, a page that was going to be about abyssal sharks and chimaeras, but at the last minute I threw in torpedo rays.