Textile is very similar to Markdown (already included with PW), though now that I've spent some time with the syntax, I think I might like Textile a little more.
Download or clone from GitHub at: https://github.com/r...ormatterTextile
Place files in /site/modules/TextformatterTextile/. Go to Modules in the admin, 'Check for new modules' and click install for Textile under the Textformatter section.
You'll also see 'Textile Restricted' and that is a separate version of the module that may be used with untrusted input like user-supplied input or blog comments. The regular Textile should only be used with trusted input.
Add this to any textarea (or text) field, and that field will interpret Textile codes and output XHTML markup on the front end of your site. Note that Textformatters appear on the 'Details' tab of the field editor when editing a text or textarea field. Use the regular 'Textile' unless the field in question may contain untrusted user input, in which case you should use 'Textile Restricted'.
Don't use this in combination with other text formatters like Markdown. Don't use with TinyMCE (there would be no point). This module may be used with any version of ProcessWire: 2.0, 2.1 or 2.2+.
Edited by Pete, 23 March 2012 - 03:30 PM.
Moved download to GitHub, Updated to Textile 2.3, added TextileRestricted version