How to convert a private key generated by ssh-keygen
lately I added a key to my Github account using their tutorial (here). So I had my private key in id_rsa. Some days ago I had to work on a github with Windows (through pageant) and I was unhappy to find that there is no real standard for the file format of private keys. Fortunately there is a solution : Puttygen (see the faq).
With this tool it's easy to load your id_rsa and get a .ppk file to give to pageant.