Apache OpenOffice: A multiplatform and multilingual office suite and an open-source project. Compatible with all other major office suites, free to download, use, and distribute

LibreOffice: A multiplatform open-source office suite, that started as a fork of OpenOffice.org. Created by the Document Foundation, an independent self-governing democratic body that was itself created by leading members of the OpenOffice.org community

Microsoft Office Online: Offers how-to articles, downloads, templates, clip art, and training