Now here's a neat and rather fun idea: a sale of original postcards by a wide range of artists, but you won't know its creator until after you've bought it.
The secret postcard sale fundraising event is being organised as part of the Royal College of Art's 18th birthday celebrations.
The 2,800 postcards have been created by the likes of Tracey Emin, Grayson Perry, Yoko Ono, Jake Chapman, Olafur Eliasson, Yinka Shonibare, Sir Peter Blake, John Baldessari.
Fashion designers such as Manolo Blahnik, Mary Quant and Sir Paul Smith have also contributed to the secret sale, as have animator Nick Park, photographer David Bailey, and film maker Mike Leigh.
Inventor James Dyson has contributed too, together with up-and-coming students and graduates from the Royal College of Art.
The postcards, which have been signed on the back by its creator, will be on display at the RCA from Friday 18th November until Friday 25th November, from 11am to 6pm each day (9pm on the Thursday). The week-long exhibition is free to enter.
And then, on Saturday 26th November, comes the sale. This is open to all and starts at 8am, running through to 6pm. Each postcard costs £45 and a maximum of four cards per person can be purchased.
On the day of the secret sale, the postcards will no longer be on display, so make sure you make a note of the ones you are interested in before you go.
Finally, and this is the important bit, you'll need an RCA Secret Collector's Number to purchase a card. To get one, click here.
The event's organisers have also announced that visitors to the exhibition can purchase a raffle ticket which could win them a place at the front of the queue on the day of the sale. The first fifty places in the queue are up for grabs.
All proceeds from the event will go towards hardship bursaries provided through the RCA Fine Art Student Award Fund. The money raised will help to ensure that the most talented artists can study at the RCA, regardless of income.
To see a selection of postcards that were contributed to last year's sale, click here. A Facebook page about the event can be viewed here.