I've heard unverified stories of people who wait around at airports until there is a vacant spot on a flight where they want to go, and then get on for insanely cheap. I would also imagine that it is theoretically possible to hitch a flight with a non-commercial plane where you want to go. I'm thinking international fares in the double digit range.
Of course, the kind of travel I'm imagining would not be comfortable or convenient. I'm thinking things that might be borderline "stowaway", but legal and ethical. I don't mean flight search websites, promotional deals, or other obvious ways of flying cheap.
Does anyone have any experience or ideas on how I could travel like this?