I picked up a copy of Weird Las Vegas and Nevada for my upcoming Mage: The Awakening Sin City chronicle, and it turned out to be a great buy. It’s full of supernatural, bizarre and otherwise offbeat stuff about Vegas and Nevada, which is perfect for a World of Darkness game.
They publish a whole series of these, too — New Jersey (two volumes — I think that’s where they started), Michigan, California and more. You can see most of the titles on the Weird U.S. site, although Vegas isn’t on there. Here in Utah, Barnes & Noble carries a good selection of them in the travel section.
At $20 a pop they’re a good buy, and the fact that they’re full of short, detail-rich writeups makes them just about perfect for adapting to gaming purposes. If you’ve got a modern game that could use this kind of color, I recommend checking them out.