OpenOffice.org is a multiplatform and multilingual office suite and an open-source project that is compatible with all other major office suites. OpenOffice.org consists of:

• Writer - a word processor you can use for anything from writing a quick letter to producing an entire book
• Calc - a powerful spreadsheet with all the tools you need to calculate, analyse, and present your data in numerical reports or sizzling graphics.
• Impress - the fastest, most powerful way to create effective multimedia presentations.
• Draw - lets you produce everything from simple diagrams to dynamic 3D illustrations.
• Base - lets you manipulate databases seamlessly. Create and modify tables, forms, queries, and reports, all from within OpenOffice.org Mathematical function creator
• Math - lets you create mathematical equations with a graphic user interface or by directly typing your formulas into the equation editor.

Read more here: http://www.openoffice.org