From the old man himself, Gygax wrote a whole book on the underworld, with an entire chapter on cant.
[ame="http://www.amazon.com/The-Canting-Crew-Gary-Gygax/dp/1931275084/ref=sr_1_1?ie=UTF8&qid=1333860245&sr=8-1"]The Canting Crew[/ame]
Also, if you watch movies like Gangs of New York, they show Cant in use during the movie.
...And then there's Planescape's chant, which is similar in many ways.