Mobile Office is an Office suite for Nokia S60 2nd and 3rd Edition mobile devices based on the OpenDocument format used by OpenOffice, StarOffice and KOffice desktop office productivity suites. You can read OpenDocument formats like OpenDocument text(.odt), spreadsheet(.ods) and presentation(.odp).

Features include:

-open OpenDocument text(.odt), spreadsheet(.ods) and presentation(.odp)
-view thumbnail image
-get information about subject, title, keywords and other meta information
-get statistics about paragraph count, words and pages
-zoom and fullscreen
-search
-view of changes

Sept Solutions is now offering a freeware version of MobileOffice for Symbian based S60 2nd Edition devices like Nokia 6600. The S60 3rd Edition version still remains a paid version.

Download here