Offsetting travel cost by selling luggage space?

If someone is flying internationally with just a back pack as a hand/carry on luggage and has an unused quota of about at least 50 lbs of luggage allowed, can the traveler sell this luggage quota of his ? The airlines don't give a hoot if you don't travel with luggage, they are not bringing down the cost of the ticket.
Where can such a luggage space be advertized and how common is it for people to sell their luggage space ?
If this luggage quota can't be sold, what can be done to offset the travel cost given that the passenger is travelling with just one bag less than 13 lbs and is allowed another 50 lbs.

Best Answer

When people still checked in with an attendent, there was basically one important question that you were always asked:

"Has your baggage been under your control at all times?"

The airport security announcement still tends to say:

"Do not accept packages from strangers."

The idea of selling your luggage allotment is tantamount to accepting packages from strangers. I doubt anyone to whom you sell would want you to examine it, and I for one wouldn't want to be the guy that smuggled the bomb onto the plane.

I'd say "Your mileage may vary," except if you did bring the bomb on board, your mileage would be significantly less than you'd like, in every instance.

There are courier companies that will sometimes pay you to be a courier, but in that case, you are taking a package that you can examine into your own luggage. There are instructions on the internet, but personally I've never found the "free flights as a courier" thing to be anything but an urban legend.

Additionally, there are other guys who are little less legitimate, and they even will afford you free accomodation for your troubles in certain instances. Only problem is that entails a commitment of 5 - 10 years. :)

tl;dr> There is no freakin' way an airline will let you do this. The security implications alone make it ~~beyond stupid~~ impractical. And you'll note, I didn't even get into the airline's revenue stream.