If you're joining a startup or a company where you're offered equity as part of your compensation package, spend some time to understand what it means. You don't have to be an expert at it, but a couple of hours of learning here could go a long way, plus that knowledge is likely to be useful again.

There's a pretty good write up at http://infochachkie.com/options/

Compensation is not everything, and for most startups the expected value of your options == $0, but you should still understand what you're getting or giving up so you can make a sound decision.