I have often said that airlines have the most perverse customer disincentives of any industry. New low today: I cancelled a seat on a flight and got a 'refund code.' The refund is less than the smallest possible flight change fee of $200. So the refund is worthless. Fine. But why would I ever cancel a segment again? Less trouble for me to just let the seat "expire" real time at the gate. Which makes it harder for them to sell. In fact, were i to do the web-check-in, they would probably be unable to sell or use the seat until minutes before the door closes.
This was USAir, but I'm sure it works pretty much the same across all carriers. The only real innovation seems to be towards the K-Mart end of the service spectrum.