That is a question I've encountered more often than I expected in the social-mediasphere and in the comments to articles written by Glenn Greenwald and others. These skeptics say: Is the National Security Agency's surveillance really excessive or over-reaching if it hasn't actually been used to violate anyone's rights or perform any extralegal activities? Does it collect anything beyond metadata of American citizens without a court order or without suspicion of terrorism-related activities? No matter what it collects, how much it collects, and about whom, is there any proof that NSA or another government agency has used any of this data to violate any rights of any American citizen?
The answer to all of these is Yes, for the following reasons.
1. We have a reasonable expectation of privacy. There is no practical, technical, legal, or other reason we should expect our phone conversations, phone metadata, text messages, private emails, internet browsing history, or any other private activities to be accessible by any employee of any government agency or private company. If anyone wants their private activities to remain private, for any reason, including merely sticking it to the government, then they have that absolute right, period. It is irrelevant whether NSA or any other branch of the federal government or any law enforcement agency has used anyone's phone/internet data to violate any other rights; their right to privacy was violated, against their knowledge and without their permission. This has indisputably happened to millions of American citizens who are not suspected of crimes, who are not guilty of any crimes, who are not connected to any terrorist group, and who are not the subject of any (legitimate) warrant.
For a good summary of the privacy violations committed on a massive scale and on a daily basis by NSA, see this FAQ by ProPublica.
2. As summarized in that FAQ, NSA records several types of activities beyond mere phone metadata: emails, Facebook posts, and instant messages; extensive details of our internet activity; and the complete audio content of an unknown number of phone calls. Regardless of the FISA Court's rubber-stamp approval process, the NSA seems to have collected data and records beyond mere metadata—data and records of people not suspected of any criminal or terrorist activity—which violates our privacy and violates the legal guarantee, specified in the Fourth Amendment, that such invasions are prohibited without a specific, individual warrant (as opposed to a broad warrant that says "we want to collect a ton of information and see if we can find any terrorists").
3. The fact that anyone wants all of this data about hundreds of millions of people is proof that they shouldn't have it. The type of person who wants access to NSA-type data is the type of person who is least fit to have it, because that's the type of person who will use it for oppressive, tyrannical purposes. This assertion is backed up by the record of every powerful government in the history of the world. General Keith Alexander, Director of the NSA, is a perfect example of this type of person. The end-goal of establishing an infrastructure like what the NSA has built and continues to build is to spy on and control every citizen it possibly can—to create a super surveillance state in which everyone is considered a suspect and in which we have no recourse when our privacy is violated and our lives are intruded upon. This is the type of state in which people are considered guilty until proven innocent, in which strident defenders of the police state rationalize all of its depredations, and in which crimes are concocted in order to justify the continuous expansion of government powers and put more people behind bars.
4. We have both a legal and a moral right for the law to apply equally to all people at all times, but powerful government officials are clearly exempt from many laws. For instance, Director of National Intelligence James Clapper should be tried, convicted, and imprisoned for lying to Congress. He could also plausibly be prosecuted for obstruction of justice. Not only will that never happen, he hasn't even lost his job or suffered anything approaching a reprimand. In all likelihood, he will retire from government service in a few months or years and get a high-paying private consulting job. Many ordinary Americans are railroaded every year by the justice system for far lesser crimes than perjury, often completely victimless crimes. James Clapper is an admitted perjurer who will never, ever suffer for it in the least bit. This is wrong, and his defenders are wrong to enable the existence of separate standards of justice for the weak vs. the powerful.
5. We have a legal and a moral right for government officials to be completely truthful to us and to keep no secrets. The Obama administration has lied about NSA's spying programs repeatedly (see here and here and here and here and here). The government is supposed to serve the people, and this requires it to be subservient. Any government that keeps secrets from the public is not subservient but rather is accumulating excessive power and doing things it shouldn't be doing. If the government has done nothing wrong, then why does it want to keep secrets from us?
It should be noted that the State is a far, far greater threat to human liberty, safety, and prosperity across the world than all terrorist groups and (private) criminal rings put together. The main reason the U.S. government, military, and citizenry face any threat of terrorist attacks is because our government is so intrusive and aggressive throughout the world, stirring up hatred and resentment and creating more terrorists than it could possibly catch or kill. Therefore, whatever secrets the State's cheerleaders claim it needs to keep, it doesn't. Being powerful, secretive, and above the law are the primary problems with all governments, so a diminution of government that included abolishing all secret surveillance programs would simultaneously eliminate most of the motivation for terrorist attacks and end the intrusive, unconstitutional surveillance of innocent people.
6. Maybe if the Obama administration and NSA would actually divulge all of the information that we have a right to, and stop lying and sidestepping and hedging and evading and re-defining words, we would become aware of more egregious activities than we already are. You could argue that governments have an interest in keeping some secrets for national-security purposes, but any person who claims the United States government has a legitimate national-security interest in more than a small portion of the data that NSA has collected on American citizens has their head in the sand and cannot be reached by facts or logic.
7. To conclude with the question posed in this post's title, yes, there is at least one identifiable American citizen whose rights have been violated by the United States government in connection with NSA's activities: Edward Snowden.
In leaking the documents about NSA programs to Glenn Greenwald, Barton Gellman, and others, Edward Snowden surely committed illegal acts, but he has done nothing wrong. He did nothing that was any more wrong than Bradley Manning did, yet he knows from Manning's example and from Obama's war on whistleblowers that he would never again be a free man if he remained on U.S. soil. The very nature of the powerful, punishing U.S. government has prevented Edward Snowden from remaining in his home country with his family and friends. The Obama administration has pursued and prevented him from settling peacefully into his lifelong exile. If he did come home, his life and liberty would be forever forfeit to the police state that necessitated his fleeing in the first place.
What was wrong and should have been illegal was for the government to implement any of these controversial programs to begin with, and it continues in its wrongdoing by failing to divulge every detail of them, at least as they pertain to American citizens. Edward Snowden has righted some of these wrongs by making them public knowledge, so he should be celebrated as a whistleblowing hero and lauded as a champion of civil liberties and limited, transparent government. He and Bradley Manning should share the 2013 Nobel Peace Prize.
It is irrelevant whether Edward Snowden violated any laws in blowing the whistle on NSA. Illegal does not mean immoral, and we should all know that the law often has little to do with right and wrong. He is the one who has been wronged by being driven from his home and pursued for extradition for actions that were not wrong but rather were noble and good.