80/20 Rule (aka Pareto Principle) - recommended book
In these blog postings, I have seen several references to the 80/20 Rule (aka Pareto Principle but which is actually a misnomer). I bought this book at a used bookstore and got a lot out of it for less than ten bucks! It's a general, very-readable introduction to the 80/20 Principle and how it can be used in various situations (including business).
80/20 Principle