I am a fan of riddles in general and mathematical riddles in particular. I have collected riddles for a couple of years and have a few hundred of them jotted down on paper and so I recently started a project on github where I write down the riddles in latex so that others may have a crack at them.
You can find the project here.
You can download the pdf generated from it here.
Here are the results of the project (you need a PDF plug in for your browser in order to see this…):