Earlier this week, Caroline took a look at VentBox, a place for people to get things off their chest. The limitation with sites like that is that they don't often solve your problems, which is where Change.org attempts to fill the gap. Change.org is designed to allow people to discuss and collaborate to make a change in a wide variety of fields. You also can vent all you want by starting your own change. It's grassroots, but on a global level.
Users can create their own cause, get others to join it, and begin discussions. You also can search out other causes and put in your own 2 cents. A significant thing that Change.org does differently from other activism sites is provide an actual planning mechanism to begin enacting user-submitted changes. You can create a pin-up board to list your "actions"--things like demonstrations and local town hall meetings that attempt to advance your cause. Events can be geotagged and are shown on a Google map. If words aren't your style, you can pitch your case by embedding a YouTube video.
Besides providing a space for specific efforts, there's also an encyclopedia of over one million nonprofit organizations like the Sierra Club and Green Peace. You can see a brief history of an organization, Change.org users who are affiliated with it, and some of the current projects that either need participation or funding. Pretty cool stuff.