I've heard people talking about courier flights; cheap fares that can be obtained in exchange for carrying a package from one place to another on behalf of a company or benefactor. Do these flights still exist, and where can they be found?
Found this article about courier flights. It says that this option is less popular and hard to find than 10 years ago because of air-deliver industry grows from that time.
Also there is many security restrictions after 9/11 event, so you can be in trouble because you don't know what exactly you have in your bag.