When I was in Germany in 2006 during the World Cup, they had an online system in place to allow people to return their tickets. They would then periodically re-release those tix into the pool . . . it was through that reissue process that I secured all of my tix.

Of course, the Olympics is a far more complex set of events, but I'd have to imagine it would have been easy to implement this year (6 years later).