CryptoMaxims for crypto applications
This is a great idea. A member of the cryptography mailing list started a wiki to develop a list of Maxims for Cryptography. I often see security practitioners criticize others for not knowing about some obscure "don't do this" from the scientific literature; but nobody ever maintains a running list of the state-of-the-art knowledge of "dos and don'ts" to help people avoid future mistakes.
Although there is something to be said for people who don't keep up with the latest in a security field of study from practicing it -- and for us to be wary of those who do so.
CryptoMaxims - Security Wiki
This page is about proper use of cryptography.