I just wanted to point to the original paper describing this encoding technique:

• http://arxiv.org/html/0901.4016 – original paper by Daniel Shawcross Wilkerson from 2009;
• https://github.com/dsw/proquint/blob/master/proquint-proposal.txt – cached plain-text version;

I found it interesting not so much for its initial purpose (encoding small binary tokens, multiple of 4 bytes like IP addresses), but as a technique of generating pronounceable passwords.