Flutterby™! : 17 cases

(You should probably use "Text" mode: URLs will be mostly recognized and linked, _underscore quoted_ text is looked up in a glossary, _underscore quoted_ (http://xyz.pdq) becomes a link, without the link in the parenthesis it becomes a <cite> tag. All <cite>ed text will point to the Flutterby knowledge base. Two enters (ie: a blank line) gets you a new paragraph, special treatment for paragraphs that are manually indented or start with "#" (as in "#include" or "#!/usr/bin/perl"), "/* " or ">" (as in a quoted message) or look like lists, or within a paragraph you can use a number of HTML tags:

p, img, br, hr, a, sub, sup, tt, i, b, h1, h2, h3, h4, h5, h6, cite, em, strong, code, samp, kbd, pre, blockquote, address, ol, dl, ul, dt, dd, li, dir, menu, table, tr, td, th