Examples of formatting errors/tips in form validation?

Question

Design

I can't find any good inspiring examples of form validation messages like "Password must be 129 words", "Username taken", etc. I climbed a dozen of all kinds of Facebook, VKontakte, but their practices did not inspire.
Surely there are reviews of this topic from the point of view of UX / UI and modern web design. But in Google come across old articles. I tried to dig on dribble, too little.
Throw articles on the topic, or some real sites where, in your opinion, it is done COOL.