Just to note, while the Stanford experiment was a pretty horrific abuse of scientific power (for which the perpetrator was rewarded with a chair at stanford), its not the reason why all experiments require ethical approval. That honour (?) goes to the Milgram studies on obedience http://en.wikipedia.org/wiki/Milgram_study
Also, that particular anecdote appears not to have a tremendous amount of relevance to the point, but on a completely tangential point, the stanford study was replicated by the BBC
ncpsychology.weebly.com/uploads/4/7/8/4/4784501/reicher__haslam_original_study.pdf
The results are extremely interesting, and somewhat counter to the interpretations put forward by Zimbardo.
The Milgram experiment is the other member of the "top two" that I refer to in the post.
I could be mistaken about the ethical approval being brought forward, but that is what I recall being taught while an undergrad at Stanford. The Milgram experiment occurred years before the SEP, and I seem to recall that the fact Zimbardo was able to get approval for this experiment (including getting the local police to help) led to a huge crackdown at universities.
I doubt there is any objective metric for choosing "the two most famous and influential psychological experiments ever conducted" but I immediately assumed you meant Pavlov's dogs as the other.
Also, that particular anecdote appears not to have a tremendous amount of relevance to the point, but on a completely tangential point, the stanford study was replicated by the BBC ncpsychology.weebly.com/uploads/4/7/8/4/4784501/reicher__haslam_original_study.pdf
The results are extremely interesting, and somewhat counter to the interpretations put forward by Zimbardo.