Do you currently use or thinking about using a cloud service like Microsoft Office 365, Dropbox, Google Drive, or Facebook to make it easier to securely share your documents in a controlled, secure fashion?
There's certainly no denying that using cloud computing to store documents has some compelling benefits. For a small monthly fee you can have anytime, anywhere access to your files, share those files securely with others, even search the contents of your documents.
The problem is that the very thing that makes it so easy for you to access, share, and search through your documents in the cloud is the very thing that makes it so easy for the NSA to find your documents and read them, without your permission or even your knowledge.
To see why, just think of a cloud service as a bank. Just as lots of people deposit their money into a central bank, people also deposit their data into cloud storage providers. From history, we know that banks made it easy for average people to safely store their money in a shared vault, benefitting from much more security than any individual could have had alone. Similarly cloud hosting providers allow many people to share in the costs of storing, securing, and accessing data.
However, because the shared bank vaults pooled lots of people's valuables into a central place, it also made the bank vaults much more attractive targets to thieves; why steal one person's money when you could steal from hundreds? Central banks also made it possible for governments to have better supervision and control over people's and corporations finances. When used judiciously, this has helped law enforcement bring criminals to justice.
Cloud hosters make the NSA's task of collecting our personal data much easier by aggregating lots of people's and business' sensitive info in one place. Now that the NSA has unprecedented powers to access central data repositories, cloud hosting providers find themselves in the same position as central banks, having to turn over any data stored on their servers over to the government. That means that not only is innocuous data like your family photos fair game for public exposure, but also more sensitive data like your medical records or your attorney's case files. (TODO: I have to remember to ask my lawyer where he stores his data.) And we've already seen that the government (or the currently dominant political party) is more than willing to use the data it collects to target rivals.
So from all us cloud computing users to the NSA, "You're welcome."