What you are considering, Punamit, would be looked at technically as file-sharing, and its legality has been, and is currently, at the center of some copyright infringement lawsuits.
At least one foreign court has ruled that "making available" copyrighted material to others is not infringement if there is no accompanying proof of distribution or downloads. But the question is largely undecided in the U.S. If you wish to be legally safe, what you share with others should only be work created by you or works in which you own the copyrights (ie, not a purchased copy of another's work that you own, but a work in which you actually have ownership in the rights).
You should not use your Cloud storage files or folders, in other words, to share or distribute works of which you are not the copyright holder, whether your intention in making these works available to others is pure or not.
What you risk with sharing files, or providing access to others to the files of copyrighted material you have uploaded, is the suspension of your account with the file-hosting company, and potentially legal action taken against you (how likely this would be would depend on the facts).
After the actions taken by the U.S. Department of Justice against Megaupload, some file services have taken steps to disable sharing and download features entirely, so that only the account holder can retrieve what they have personally uploaded. This was not done so that the account holders could circumvent these disabled features by providing direct access to others to their file contents.
For some additional reading, you may wish to check out the Anti-Counterfeiting Trade Agreement (ACTA, also known as the "Piracy Treaty") that was formed between several countries late last year. The Treaty covers not only illegal trade in counterfeited goods, but also addresses P2P file sharing and Cloud storage. Obviously this Agreement was reached to deal with the most egregious of copyright offenders (and counterfeiters), but it can give you a clue as to how governments around the world are viewing Cloud storage, and how seriously copyright infringement, and IP infringement in all forms, is being taken.