Back in '95, I worked on a project in New Haven - there were a large number of us flying from DC to CT every week.

I was right out of college and had just started flying so I certainly didn't know how to work the system back then.

Each Monday morning there was a 7:40am IAD-HVN flight (J31 - 19 seats!) and a 7:55am flight IAD-BDL. The HVN flight was oversold almost every week, so one of my coworkers made this his routine:

Book the HVN flight, take the VDB, take the BDL flight, and get a ride down to New Haven from Hartford with other coworkers who were already booked on the Hartford flight.

I don't know how many free tickets or vouchers he ended up receiving but I'm sure it was quite a lot. Don't know if this would be allowed today (would you get flagged if you took to many VDB's??), but I guess back then there was no limit...