Agaric needs to do this with a Drupal photo gallery

• Internal paths in single or double quotes, written as "internal:node/99", for example, are replaced with the appropriate absolute URL or path. Paths to files in single or double quotes, written as "files:somefile.ext", for example, are replaced with the appropriate URL that can be used to download the file.
• You may post code using <code>...</code> (generic) or <?php ... ?> (highlighted PHP) tags.
• You can use Markdown syntax to format and style the text. Also see Markdown Extra for tables, footnotes, and more.
• Web page addresses and e-mail addresses turn into links automatically.
• Allowed HTML tags: <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd> <img> <blockquote> <small> <h2> <h3> <h4> <h5> <h6> <sub> <sup> <p> <br> <strike> <table> <tr> <td> <thead> <th> <tbody> <tt> <output>
• Syntax highlight code surrounded by the {syntaxhighlighter SPEC}...{/syntaxhighlighter} tags, where SPEC is a Syntaxhighlighter options string or "class="OPTIONS" title="the title".
• Lines and paragraphs break automatically.

More information about formatting options