I don't think this has been posted before but I just saw this and wanted to share.
If you're flying into Germany or are in Germany and really want to be spontaneous you can do a
blind booking with German Wings. Its only supposed to be 20 euros, taxes included.
"Exactly where you end up flying to remains a surprise until you complete your booking. You decide when and from where you depart from and what suits you.
Simply choose your departure airport and your desired travel theme by clicking on one of the themes "Party", "Shopping", "Snow", "Metropolis Easteurope", "Metropolis Westeurope" and "Culture"."
Blind Booking
Threaded Mode