Doritos has launched a packet of crisps without specifying the flavour. Instead they've called it X13D and left it to the customer to decide what it is. Here's their explanation: "This is the X13 deep flavour experiment where we created a bold new mystery flavour and then decided to do something we've never done before - leave the rest up to you." It's a brilliant example of a physical social object and open source marketing. I mentioned it at a session Johnnie and I did this morning where we presented our Co-Creation Rules manifesto and everyone immediately smiled. And of course, the online buzz is off and running. Best piece of modern marketing in 2007 for me.