There are numerous questions asking whether a specific behavior is "ethical" on Stack Exchange sites. Such questions are difficult (well, impossible) to answer without a code of ethics or a set of behavioral guidelines to evaluate the behavior against.
There are the FAQs, which do lay out some behaviors (i.e. rudeness is not tolerated, promotions are usually discouraged by community members, the types of questions that are considered appropriate, etc.), but the FAQs do not go so far as to make any statements about many other behaviors. For instance, "gaming" the reputation system is not considered an appropriate behavior (see this post and this other post, and there may be other, more subtle behaviors that many users might consider to be unethical, such as posting and answering questions on how to unlock cell phones.
Other than the specific behaviors listed in the FAQ, and actions moderators take in response to flagged posts there are no formal ethical guidelines that dictate which behaviors are ethical or not.
Are these measures sufficient, or should Stack Exchange consider creating a formal set of ethical guidelines?