I love the concept of CipherSaber, which is nothing more than a bit of protocol around RC4, creating a secure cryptosystem which is simple enough to pass by mouth. The challenge is that you implement this with your own program, which is at most a 60 minutes excersize for an average programmer.
A natural thought, therefore, is to collect all these programs on a list, which I intend to do on the CipherSaberList. Entries both in computer and natural languages are welcome.