Slacktivism (sometimes slactivism) describes "feel-good" measures in support of an issue or social cause, that have little or no practical effect other than to make the person doing it feel satisfaction.
No offense to anyone doing it, of course, but this has the same effect as most online petitions, chain letters, etc.
If you really want to fight for a cause and bring about change, donate money or volunteer your time. I don't expect any change to come from "donating my facebook status for an hour" to the troops or posting the color of my bra for Breast Cancer awareness.