Vault 157 (completely made up for now of course)
A vault located in Vancouver, Washington designed to be a breeding ground for an endangered animal to be voted by the population of people in the vault, the black-footed ferret was chosen. After years of living with minor radiation the humans finally snapped and left, the ferrets remaining seemingly unchanged by the mutations. after the years these ferrets were left alone they began to form a semi-sentient society within the now humanless vault. this Vault was made larger than usual to support humans and ferrets, though it is now overrun with super-intelligent Ferrets who have learned by accessing terminals, much like Fawkes. These ferrets live much longer than normal ones before the war and are slightly larger with more articulate hands. This vault spans the entire underground of the town while nothing but a Raider camp makes up the above-ground section.
The Courier, hero of New Vegas, has been called to a nearby plateau. on top he finds a man who wants to take him to Lehighton, otherwise known as the Ferret Underground, in a shiny new Vertibird.
I do not have too many ideas for exclusive things for this but among them would be
-an exclusive follower (one of the ferrets with no more story behind him than this so far)
-ferret-developed weapons (mostly melee, made larger especially for you)
This will be open to more discussion and I will edit this a lot, I may have an impact on the future of this game (or not, but it's an adventure.)
Credit to http://www.gamesas.com/bgsforums/index.php?showuser=597410 for the idea of placing this in Washington instead of Pennsylvania.