The usual reward for this is a voucher generally good for a flight comparable to the one you were been bumped from.

From an airline perspective, empty seats are lost revenue. Airlines routinely overbook flights by 4-6 percent, because on average, that's the number of people who miss connections, have to cancel at the last minute, or otherwise can't make the flight.

For something close to 80 percent of all airline flights, this overbooking isn't a problem. For those 20 percent of flights where it is, it can be a great inconvenience or a great opportunity.

Airlines offer vouchers rather than refunding airfares to your purchasing mechanism for two reasons. The first is time; it often takes 24 hours or more to process a credit card refund, and that takes more labor on their part to make it happen.

The second is that a surprising number of vouchers don't get used. If you're bumped from a flight, make a fuss and you can usually get more than a voucher. Ask for two tickets or three.

Ask for hotel credits or gift cards to restaurants. If you're using an airline miles program, ask for bonus miles. Don't be afraid to show your irritation when doing this; the airlines give out vouchers to stifle complaints, and remember that you're aiming to get the best reward possible for your inconvenience.

If you absolutely have to make a connecting flight, and you have cash on you, find out how many volunteers need to voluntarily bump themselves off a flight, and look for likely candidates.

College students waiting in a terminal are good candidates for this - a hundred bucks out of your pocket means they may volunteer when otherwise they would not. Take notes and get receipts - you can take the airline to small claims court and get reimbursed.

The second strategy is having a flexible schedule; I routinely plan my flights on the assumption that I will volunteer for bumps to get the voucher for my next business trip.

I had a two year streak going where, by taking bumps, I did not have to pay for a single trip. Just be prepared for sitting in a terminal if this is the case.

If you volunteer to take a bump, be polite about it, but remind them that you're doing them a favor, and see if you can get a voucher plus airline mines, or hotel accommodations, or an extra ticket.

Using vouchers requires a bit of forethought and planning. First of all, make sure you store them in a safe place, and write down the date that they expire.

Whenever you're booking your next travel run, use the vouchers first before paying any money to cover the airfare. Remember, airlines are counting on the fact that most vouchers end up unused - use them to your advantage when you get them; be aware that some airlines put blackout dates on vouchers; this is why it's better to use them earlier rather than later.