config.rb

# add this to your config.rb

ready do
  wikitargets = Hash.new
  wikiwords = Hash.new

  sitemap.resources.select {|p| p.ext == ".html" }.each do |p|
    unless p.data['wikitag'].nil?
      wikitargets[p.data['wikitag']] = p.url
    end
    File.open(p.source_file).each_line do |line|
      re = /\<\%\=\W?wiki\(.*?,\W?[\'\"](.*?)[\'\"]\)\W?\%\>/
      line.scan(re).map(&:first).each do |match|
        if wikiwords[match].nil?
          wikiwords[match] = 1
        else
          wikiwords[match] += 1
        end
      end
    end

  end

  Middleman::Application.set(:wikitargets, wikitargets)
  Middleman::Application.set(:wikiwords, wikiwords)

end

helpers do
  def wiki(text, tag)
    wikitargets = Middleman::Application.defaults[:wikitargets]
    if wikitargets[tag].nil?
      text
    else
      target = wikitargets[tag]
      "<a href=\"#{target}\">#{text}</a>"
    end
  end
end

wikitag-list.html.erb

<%
  targets = Middleman::Application.defaults[:wikitargets]
  words   = Middleman::Application.defaults[:wikiwords]

  words_sorted = words
                  .sort_by { |word, count| count }
                  .select {|w| targets.assoc(w[0]).nil? }
                  .reverse!
%>


<h4>Unlinked Words</h4>

<table class="table table-bordered">
<% words_sorted.each do |word| %>
<tr>
  <td><%= word[0] %></td><td><%= word[1] %></td>
</tr>
<% end %>
</table>

<h4>Available Targets</h4>

<ul>
<% targets.each do |key, value| %>
<li><%= key %><br /><small><%= value %></small></li>
<% end %>
</ul>