Watch for Waste - Millions of tickets go unused, even though most non-refundable fares are valid for travel for up to a year.
A couple of months ago in between visits to Iraq and Eastern Europe, I even double-booked myself on two completely non-refundable flights home to Seattle.
Should you be denied a visa, you can always re-apply with additional documentation, but each time you do so, you will have to pay the non-refundable $100 visa application fee.
ChangeYourFlight provides an alternative for these non-refundable tickets, with airlines providing a partial refund without any change fee.
BBC: New sites let you sell unused trips
Theaters and sports teams sell non-refundable tickets, but buyers can give them to friends or sell them.
WSJ: Airline Cancellation Fees and Penalties Are a Big Business
All packages are charged in full at time of booking and are non-refundable.
FORBES: Tax Day Specials, Promos And Freebies