EU Cookie Compliance - let's start a good practice

With regards to the EU directive as per cookie opt-in, I would vote for working out some kind of a good practice for developers (mostly module developers) to explicitly document the cookies used by their code, their purpose, their lifetime, their impact on user experienced (logged in and anonymous). I think this would be a good support for site owners as well as site builders, esp. in maintaining of their cookie policy documents.
A file "COOKIES.txt" in the root folder would be just great.
Although the directive has been already in effect in some EU countries for some time, I don't think it's too late to have this kind of practice, and to have the developers provide the cookies details.