(Via rodcorp) trade tricks is a kind-of "catalog of secrets only its employees are aware of—such as how waiters with heavy platters know to look straight ahead, and never down". My favorite:

Proofreader: If you’re reading too fast, your brain can “correct” typos, preventing you from catching them. That’s why it’s sometimes a good idea to read a page upside-down. It forces you to pay closer attention to individual words out of context, and you can’t race through pages too fast.
High School Teacher: When the students are acting up (or your performance is being evaluated) , turn on the air conditioning as high as it goes. The students are far better behaved when they are frozen. Note: the opposite effect does not work: excessive heat only exacerbates the issues of problem children.