When people ask me what kind of law I practice, one of the things I say is "wage and hour cases." That's way too nice a description. From now on, I will say, "I prosecute wage theft." If someone knocks you down and takes your purse or wallet, it's "robbery." If they break into your home or car and take something, it's "burglary." If Bernie Madoff takes your life savings, it's "fraud." They are all thefts of your money.
And if your employer does not pay the wages you are due -- and are owed according to the law -- then it is a theft of your wages. As Kim Bobo points out in "Wage Theft: Faces of a Hidden Crime, Part 1 of 3", wage theft is not paying the minimum wage, not paying for overtime, wrongly classifying an employee as a "contractor" so no benefits are paid (and usually no overtime), taking illegal deductions, and not paying employees at all.
While the production values on "Wage Theft" are low, the information is high quality. After you watch Part 1, go on and look at Part 2 (mainly about Interfaith Worker Justice) and Part 3 (in which there is a resolution of the problems presented in Part 1).
Interfaith Worker Justice has a great page of resources on wage theft.