MusicRadar has never really understood the concept of sending 'gifts' on Facebook – you can't get merry by looking at a picture of a pint of beer, can you? – but if that's what you're into and you like classic hardware synths, you'll probably get plenty of mileage out of the new Analog Synths application.
True to form, this enables you to send your friends pictures of various legendary instruments, including a variety of Moogs, a couple of ARPs, Roland's Juno 106 and the Buchla 100 series. None of these actually has any practical use, obviously, but people who exchange Facebook presents don't seem to care about such trivialities.
Of course, if you want to send one of your friends an instrument that they can actually play, you might do better to fire off a link to MusicRadar's guide to the best free plug-in synths.