Finally a nice solution for mapping relative urls

plugins/category_generator.rb

@@ -130,7 +130,7 @@ module Jekyll
     #
     def category_links(categories)
       dir = @context.registers[:site].config['category_dir']
-      root_url = @context.registers[:site].config['root']
+      root_url = @context.registers[:site].config['root'].sub(/\/$/, '')
       categories = categories.sort!.map do |item|
         "<a class='category' href='#{root_url}/#{dir}/#{item.gsub(/_|\W/, '-')}/'>#{item}</a>"
       end

plugins/custom_filters.rb

@@ -20,15 +20,23 @@ module OctopressFilters
   end
 
   # Replaces relative urls with full urls
-  def full_urls(input, url='')
-    url ||= ''
+  def expand_urls(input, url='')
+    url ||= '/'
     input.gsub /(\s+(href|src)\s*=\s*["|']{1})(\/[^\"'>]+)/ do
       $1+url+$3
     end
   end
 
-  # Returns a url without the http:// for use in as a search modifier eg. 'search terms site:website.com'
-  def search_url(input)
+  # Removes trailing forward slash from a string for easily appending url segments
+  def strip_slash(input)
+    if input =~ /(.+)\/$|^\/$/
+      input = $1
+    end
+    input
+  end
+
+  # Returns a url without the protocol (http://)
+  def shorthand_url(input)
     input.gsub /(https?:\/\/)(\S+)/ do
       $2
     end