3BOpenDoc ensures that interoperability is not a barrier to organizations when looking at adopting ODF. 3BOpenDoc allows users to seamlessly exchange OpenDocument Format (ODF) files with users of other document formats, by converting ODF files ‘on the fly’ as they are emailed or viewed/checked-out of a document or content management system. 3BOpenDoc can convert ODF to and from many file formats including Microsoft Office.

A cross-platform word processor running on most Unix systems, MS-Windows and MacOS X, featuring read-write support for ODF text files (.odt)

The Katholieke Universiteit Leuven (K.U.Leuven) created an extension for OpenOffice.org Writer and LibreOffice Writer that enables users to evaluate and repair accessibility issues in word processing documents.

Alfresco is an open source enterprise CMS. One of the supported file formats is ODF.

From their website: "A project that aims to become an office suite for Android (a software development platform for mobile devices created by the Open Handset Alliance). In principle we are just working with the Open Document formats, used today in Open Office and other platforms."

A lighweight python script to anonymize ODF files, it removes pictures, meta.xml and replaces digits and text.

Apache Tika - a subproject of Apache Lucene - is a toolkit for detecting and extracting metadata and structured text content from various documents using existing parser libraries. 
Support for ODF was added in Tika 0.3.

The ODF backend for AsciiDoc enables AsciiDoc users to directly convert documents from AsciiDoc to Open Document Format v1.2.

AsciiDoc is a lightweight markup language that maps to DocBook semantics and makes writing (technical) documentation and presentations more enjoyable as it removes styling and formating from the creative process.

AsciiDoc is useful in the following cases:

Aspose.Words is a class library that enables your application to perform a great range of Word® documents processing tasks without utilizing Microsoft Word®. With Aspose.Words you can generate, modify, convert, render and print documents. Aspose.Words supports DOC, OOXML, RTF, HTML, OpenDocument, PDF and other formats.

Atlantis is a customizable and fully portable word processor for MS-Windows. Version 1.6.5 supports ODF (import only).