Brussels Airlines have what they call a ‘’ sale whereby you can purchase a voucher for a return economy flight for EUR99. The catch is that you have to buy the voucher first and then wait until 05 January 2015 to redeem. They do say that they have 120,000 seats available on 8,000 flights on 32 different routes so hopefully there will be availability. If you or the person to whom you gift the voucher is unable to redeem on one of the promotional flights, you or they can use the amount as credit toward any other flight.

There is another useful line in the Terms and Conditions:
You may inform us of your wish to withdraw from your purchase of a within 14 days of the purchase without giving any reason. In such a case, we will reimburse you the entire payment within 14 days of receipt of your notice.

These vouchers can be purchased between Tuesday, 18 November 2014 and Sunday, 28 December 2014. So you could theoretically purchase on the 24 December and if you couldn’t find a promotional flight on the 5 January, you could still ask for money back. I plan on purchasing as late as possible to give myself as much time to try and book or cancel.

The voucher can be redeemed for any return direct flight between the following:

Brussels to/from Barcelona, Berlin, Bilbao, Birmingham, Bologna, Bristol, Budapest, Copenhagen, Edinburgh, Geneva, Gothenburg, Hamburg, Hannover, Krakow, Milan Linate, London, Lyon, Madrid, Manchester, Marseille, Milan Malpensa, Nice, Oslo, Prague, Riga, Rome, Toulouse, Turin, Venice, Vienna, Vilnius, Warsaw

The site is slightly misleading as it looks at first that your journey must originate from Brussels, but the T&Cs expand on this and from what I can see, your return flight can originate from of the cities on the list. All flights are between Brussels and the list of cities above.

The redemption period is from Monday, 05 January 2015, until Tuesday, 31 March 2015. This can be for flights between 15 January and 15 June 2015. The booking must take place two weeks before departure

The good part of this offer is that the EUR99 covers 23 kg checked baggage, 12 kg hand baggage, seating together and all taxes included. You can also claim 15% off an Uber taxi ride.

If you are a Miles & More member, you earn 500 miles per voucher purchased. I doubt whether you will earn points on these flights but if you have a Star Alliance card that provides lounge access then that will improve your journey.