Domain: Archaea
Phylum: Euryarchaeota
Class: Thermococci
Order: Thermococcales
Family: Thermococcaceae
Genus: Pyrococcus
Species: Furiosus
A weird little microbe. You might think you like warm weather, but these guys thrive best at approximately 100 degrees Celsius (212 degrees Fahrenheit)--which is hot enough to kill most things---though it can grow in temperatures anywhere from 70C to 103C. These temperatures, along with the preferred 2.5% salt concentration, can be found in undersea hot vents.
So really hot, no lack of salt...what else? Well, down there you'll find an absence of sunlight, not much oxygen, and an abundance of pressure--a mind-squishing 200 atmospheres. Preferred Ph. is 7 (water), but anywhere from 5-9 works.
Like the cockroach, it will be around after we go MAD, being able to withstand radiation doses up to 1500 gray. For comparison, it takes 10-20 grays to kill you. No source wants to give me a real number for cockroaches, but they seem to agree that it takes 'over 1000 grays'.
It was first discovered in 1981 in Vulcano Island, Italy, and later described in some detail by Dr. Karl Otto Stetter and Dr. Gerhard Fiala in 1986. In 2001, it was fully sequenced. (Of the three sequenced Pyrococcus, Mr. P. furiosus has the most base pairs, at 1 908 256.)
For those wondering about the name, 'Pyrococcus' means fireball or fireberry (they're round and like the heat), and 'furious' means rushing (or mad, filled with rage, or, hey, how about furious?) due to P. furiosus having one of the shortest generation times among the Archaea--37 minutes in optimal conditions.
Sources / Further Reading
http://en.wikipedia.org/wiki/Pyrococcus_furiosus
http://www.ebi.ac.uk/2can/genomes/archaea/Pyrococcus_furiosus.html
http://microbewiki.kenyon.edu/index.php/Pyrococcus