Extending OpenOffice.org: Checking grammar with LanguageTool
One of the features that many users dearly miss in OpenOffice.org is a grammar checker. Fortunately, LanguageTool fills the void, adding grammar-checking capabilities to OpenOffice.org.
Although LanguageTool is probably not on par with the grammar checker offered by Microsoft Office or other commercial closed source office suites, it does have one important advantage: you can easily define new grammar rules. The current version of LanguageTools supports several languages besides English, including German, Polish, French, and Dutch. The degree of support varies from language to language; right now the most supported language is Polish (it includes 579 grammar rules), followed by English (221 rules) and Dutch (198 rules). You can see a full list of the supported languages at LanguageTool's Web site.
You can install LanguageTool like any other OpenOffice.org extension.