I haven't worked for a start-up, but from hanging out on HN for a few years I can tell you that equity not necessarily common, but not really rare either. One

I haven't worked for a start-up, but from hanging out on HN for a few years I can tell you that equity not necessarily common, but not really rare either. One thing to keep in mind, is that most start-ups fail, and most successful start-ups don't turn the early employees into millionaires. I've often heard the advice that you should just look at any equity/options offered as a bonus, and negotiate for a fair wage. At the very least you should go in understanding that you are potentially giving up income for equity that may or may not ever be worth a lot of money.