This may seem to be an odd, confusing question, so I will first explain what this means:
Cloud computing allows all people to share their computer's unused processing power to a number of projects with almost no effort or cost to themselves. For example, the World Community Grid allows one to donate processing time to cancer research, clean energy research, fighting AIDS, and numerous other projects. Other projects through other organizations include searching for life outside of our solar system.
So my question is, since it would have no noticeable affect on one's computer and would use a trivial amount of power when the computer is used anyway, is it unethical to NOT do this?
The inspiration for this question comes primarily from Engel's Day Old Bread argument against beef (you may see Engel's Day Old Bread argument here on page 10).