As part of its "Technology for Good" program, Microsoft now distributes free user licenses of Office 365 to eligible non-profit organizations, thus giving them access (for free or at a minimal cost) to all or part of collaborative productivity tools and services of cloud version of Microsoft Office. This special offer from Microsoft is to open to non-profit organizations involved in different areas such as the promotion of culture, assistance to disadvantaged people, the promotion of human rights and the emergence of civil society.
Several Office 365 formulas are available (from small organizations to large organizations). "Office 365 for Nonprofits" give access to the different tools of the online suite: business email, Office Web Apps, video conferencing, etc.. The offers varies depending on the size of the organizations.
Note that Office 365 for Nonprofits is not completely separated from the commercial offers from Microsoft: the organizations have the ability to subscribe to the desktop version of Office 365, at a preferential rate.