KOffice is a free integrated office suite for KDE. It includes a host of productivity applications.
So of course there's a word processor (KWord), a spreadsheet (KSpread) and presentation tool (KPresenter). All can import documents created by similar suites, like Microsoft Office 2010, though with varying degrees of success (you'll need to try it to see how well this works for you).
Other tools provided include KPlato (project planning), Kivio (diagramming), Karbon (a vector graphics tool), Krita (image editor and painter), and the excellent Kexi (database creation and management).
The suite went through a major architecture change at version 2.0, which means that it's not as stable or reliable as the 2.3 version number would suggest. It is a significant step forward, though, and so if you're looking for a free office suite then it's worth giving this one a try.