Request a meal voucher if a delay extends through a mealtime. If the delay extends past 1 a.m. request a hotel voucher. Airlines will not provide meal or hotel vouchers at the origin of a flight. Avoid traveling at peak times. Getting upset doesn't help.
Airlines ask for volunteers to give up their seats and they receive compensation for doing so.
If you are not in a rush you can sell back your seat. Before you do, find out what airline can confirm your seat, and what amenities such as free meals, hotel rooms, telegrams, or transportation will be provided. Airlines may bargain with you. If you are bumped, ask for a written statement of your rights. If the airline can get you to your destination by any means within an hour of your expected arrival time, there is no compensation.