In the past I've heard about a scheme to prove your identity online in places like forums, without having to create an account.
When posting, the user would enter a password which is then heavily hashed and displayed publicly along with the post. This way the user can prove his identity between posts without having to create an account with a fixed name and password.
I'm not sure what to Google for. So far I've found the term "commitment scheme" on Wikipedia, but googling further on that, I can't find other places using it (though I'm sure there have to be some).
Does this kind of commitment scheme (publicizing a password hash) have a name?