OpenOffice.org is a multiplatform and multilingual office suite and an open-source project. Compatible with all other major office suites, the product is free to download, use, and distribute.
Pros: OpenOffice.org is a free and easy-to-use alternative to most commercial office suites, including (but not limited to) Microsoft Office. OpenOffice.org is a cross-platform application for Mac, Windows, Linux, Solaris, and FreeBSD.
Cons: OpenOffice.org for Mac OS X requires the use of Apple’s X11.app window system.