This plugin provides a simple plain-text view of a post's raw content before the various content filters and transformations are applied.
As such, it's intended for use with input which is filtered through systems such as Markdown or Textile before display. If you prefer to write with a rich-text editor, such as that included in WordPress 2.0+, it is not for you.
Download the plugin here.
Drop it in your plugins folder and you're ready to go. If you are a user of WordPress 1.5.x, you may need to regenerate your rewrite rules.
To get a link to the text version of a post, use this:
<?php echo Plaintext::link(); ?>
Depending on your URL structure, the link should look something like this:
http://example.com/index.php?p=10&plaintext=true
http://example.com/archive/2005/11/12/post-name/text