Please let me know if there are any efficient English grammar checkers available for gedit or LibreOffice on Ubuntu 11.04.
LanguageTool: An Open Source style and grammar checker for English, French, German, Polish, Dutch, Romanian, and other languages. You can think of LanguageTool as a software to detect errors that a simple spell checker cannot detect, e.g. mixing up there/their, no/now etc. It can also detect some grammar mistakes. It does not include spell checking.
LanguageTool will only find errors for which a rule is defined in its XML configuration files. Rules for more complicated errors can be written in Java.
LanguageTool requires an external link to Java 5.0 or later. The current version only works with OpenOffice.org 3.0.1 or later and LibreOffice and you need to restart OpenOffice.org/LibreOffice after installation of this extension.
Installation and Usage
In OpenOffice.org/LibreOffice: Double click LanguageTool-1.3.1.oxt to install it. If that doesn't work, call Tools -> Extension Manager -> Add... to install it. Close OpenOffice.org and re-start it. Type some text with an error (e.g. "This is an test." – make sure the text language is set to English) and you should see a blue underline.
Also see Usage for using LanguageTool outside of OpenOffice.org.