cheat sheets.

rdoc:

Normal Paragraph text
  def indented_text()
    # is treated as code -- not reformatted
  end

Lists:
  * This is a list element
  - This is one too.
  1. This one will be numbered
  [label] item description,
          can be continued at same
          indent level
  label::
    or start the description on the following line
    and continue at the same indent level

----------------------------------------------------------------------
Three or more hyphens make a horizontal rule on the page

Styling:
  = Level One Heading
  == Level Two Heading
  _italic_::                  _word_ or <em>text</em>
  *bold*::                    *word* or <b>text</b>
  +typewriter+::              +word+ or <tt>text</tt>

Auto hyperlinked:
 MyClass
 my_class.rb
 def my_method; end;
 #my_method
 http:, mailto:, ftp:, www.
 link: (to local filesystem relative to --op)
 (urls to images are rendered as inline image tags)
 label[url] (uses label as hyperlink text)
 {multi word label}[url] (uses label as hyperlink text)

Ruby:

  ClassNames, source_files.rb and either method_name_having_an_underscore
  or #methodnamewithhash are hyperlinked to their documentation.

  :title:The title for the document.

  # documenting this function
  #--
  # this will not appear in the docs (shhh....)
  #++
  # this will appear (hi!)
  def foo() # :nodoc:
    # this function won't appear in the docs
  end