Spellchecker.net lets you copy and paste text into an online tool to quickly identify spelling and grammar errors. An online thesaurus is also available for your convenience.

AbiWord is a free open source word processing program that includes a grammar checker. It is supported on all of the most common operating systems, including Linux, Mac OS X (PowerPC), and Microsoft Windows. The interface is similar to Microsoft Word, making this program very easy to use. Import and export filters let you convert documents to HTML, Rich Text Format, and OpenDocument for greater convenience.

Language Tool is a free open source grammar checker that is designed to help users identify the most common grammatical mistakes in their text. Language Tool works to detect errors in English, German, Dutch, and Polish, but limited support is also available for French, Spanish and Italian. However, it is important to realize that Language Tool does not contain a spell checking program.

Grammar Slammer is a spelling and grammar checker that uses a taskbar and integrated search to help identify errors in a document and suggest corrected text. You can download a free 21 day trial of this program or purchase the full version of the software for $49.