Socks, space flights and beer tasting among world's oddest airline rewards

Join a frequent flyer program, and conventional wisdom suggests that you'll be rewarded with flights for the points that you build up with your loyalty.

However, airlines are increasingly turning toward other methods to reward their members, a new study suggested this month, with increasingly wacky rewards on offer for those that can stack up the miles.

The IdeaWorks company, which reviewed the frequent flier programs of over 150 airlines, concluded earlier this month that airlines were turning to "wild, weird and wonderful rewards" to woo their members.

Rack up 386 million miles with Etihad Aiways, for instance, and you'll be able to redeem a $3.5-million 68-foot Azimut yacht, the most expensive reward found to be on offer during the survey.

Pick up 25 million points with Virgin, similarly, and you can redeem for a $200,000 flight on Virgin Galactic when it blasts off towards space later this year, while 2.3 million points will earn a 270-mile trip in a private jet from Lufthansa.

Madonna concerts, a vest autographed by George Clooney and a stay on Richard Branson’s private island are among the other rewards now on offer from airlines, IdeaWorks found -- but rewards aren't reserved only for those with millions of points.

For just 650 miles on Icelandair, guests can pick up a slice of what the airline describes as '“Happy Marriage Cake” to eat on board.

In a similar vein, Finnair offers a cookery course at the Helsinki Culinary Institute, American's AAdvantage offers a beer tasting tour in Brussels, Belgium, and after all that, Bangkok Airlines were found to offer health checkups for travelers who accrue enough miles.

Perhaps the oddest award found was from Lufthansa's Miles & More, which promised regular deliveries of socks thanks to a “Sockscription” from Blacksocks.com, for just 21,000 miles -- enough to wear out anybody's socks.