Intelligence: All That Matters

An excellent and accessible introduction to the science of intelligence. The subtitle is a little tongue in cheek

It's a quick, interesting read. I've found myself estimating the IQ of people around me since reading it; though I'm not sure that's necessarily good for me or my relationships. Nevertheless, it's fun, and I wouldn't be doing it if I hadn't read this book. Give it a go, it will only take an hour or two, and you'll probably come away knowing a thing or two.