A colleague of mine was flying IAH-PHX on Sunday 12/28. He was schedules to be on the ER4 evening flight.
At the gate they paged for volunteers offering a seat the next morning in F and a $300 voucher. He walked up and said that he didn't need a hotel and because of that, would do it for $500. The woman immediately accepted and printed his voucher.
When he went to fly back Monday, he heard someone paged at the gate and given a BP for 2B, the seat printed on his BP. When he approached the gate agent they told him his reservation had somehow been canceled and they had to rebook him in Y. They gave him his new BP with another voucher for $250.
All told, he walks away with $750 in vouchers. He hadn't even joined Onepass until I finally convinced him to today.