The subcultures covered in this nifty little book include Americans in Antarctica, beekeepers and birders, cat fanciers, cavers, magicians and mediums, online gamers, puppeteers, scuba divers, snow blowers, truckers and UFO believers. All in all, 65 is a wealth of lingo, from grognard (gamer) to rettysnitches (ham radio operators).
In my household, this book has been wandering from room to room because it's a fun book to dip into. The terms are lively and intriguing. Who wouldn't enjoy finding out about what fantasy notes and body bags mean to coin collectors, or learning where a motorcycle's "jesus clip" is?
Beyond that, I've had occasion to dip into it a couple of times now to find just a couple of words to seed into a piece of dialog to give it a more authentic feel. The section on goth culture gave me some of the words I used for "Niobe in the Seattle Rain", which is appearing soon from Dark Recesses as well as some of the circus lingo in "I'll Gnaw Your Bones, the Manticore Said." While I wouldn't go too heavy-handed with this method, I think one or two (I would probably never go more than three, unless it was for a deliberate effect or a very long piece) carefully salted into a story can go a long way to establishing the world in which the piece is set or the character using the expressions.
The book could also be used to generate writing exercises by taking one or two terms and using them in a passage of description, scene, or piece of dialog. Or combing two very different terms to create a title or writing prompt.
All in all, for $15, this is a good and useful book well worth having on a writer's reference shelf. I highly recommend Talk the Talk: The Slang of 65 American Subcultures, which is available from Writer's Digest Books.