How to set up a treasure map?

If I were to send 1 BTC to some address, all one would need to steal that money is the corresponding private key. Since a private key is nothing more than a 256-bit number, I was thinking about making a treasure map of sorts.

Code:

E9 87 3D 79 C6 D8 7D C0 FB 6A 57 78 63 33 89 F4 45 32 13 30 3D A6 1F 20 BD 67 FC 23 3A A3 32 62

for example, is a private key. So what sort of treasure hunt can I create that will make it possible for someone to discover the private key and therefore win the bounty?

I'm imagining a series of clues (think National Treasure), but not too obvious. If it's to be a world-wide hunt, it must therefore be difficult to crack. I don't want to hide the private key on a website or anything, but rather have the pieces be freely found in the public. So perhaps

Code:

could represent the 233rd page of some book and so on.

Would love feedback and ideas.