diff --git a/lib/jekyll/filters.rb b/lib/jekyll/filters.rb
index e76fa755..ff13a233 100644
--- a/lib/jekyll/filters.rb
+++ b/lib/jekyll/filters.rb
@@ -51,12 +51,12 @@ module Jekyll
     # Slugify a filename or title.
     #
     # input - The filename or title to slugify.
+    # mode - how string is slugified
     #
-    # Returns the given filename or title as a lowercase String, with every
-    # sequence of spaces and non-alphanumeric characters replaced with a
-    # hyphen.
-    def slugify(input)
-      Utils.slugify(input)
+    # Returns the given filename or title as a lowercase URL String.
+    # See Utils.slugify for more detail.
+    def slugify(input, mode=nil)
+      Utils.slugify(input, mode)
     end
 
     # Format a date in short format e.g. "27 Jan 2011".
diff --git a/lib/jekyll/utils.rb b/lib/jekyll/utils.rb
index a84847a4..ba0303a4 100644
--- a/lib/jekyll/utils.rb
+++ b/lib/jekyll/utils.rb
@@ -104,21 +104,53 @@ module Jekyll
 
     # Slugify a filename or title.
     #
-    # name - the filename or title to slugify
+    # string - the filename or title to slugify
+    # mode - how string is slugified
     #
-    # Returns the given filename or title in lowercase, with every
-    # sequence of spaces and non-alphanumeric characters replaced with a
-    # hyphen.
-    def slugify(string)
-      unless string.nil?
-        string \
-          # Replace each non-alphanumeric character sequence with a hyphen
-          .gsub(/[^[:alnum:]]+/i, '-') \
-          # Remove leading/trailing hyphen
-          .gsub(/^\-|\-$/i, '') \
-          # Downcase it
-          .downcase
+    # When mode is "none", return the given string in lowercase.
+    #
+    # When mode is "raw", return the given string in lowercase,
+    # with every sequence of spaces characters replaced with a hyphen.
+    #
+    # When mode is "default" or nil, non-alphabetic characters are
+    # replaced with a hyphen too.
+    #
+    # When mode is "pretty", some non-alphabetic characters (._~!$&'()+,;=@)
+    # are not replaced with hyphen.
+    #
+    # Examples:
+    #   slugify("The _config.yml file")
+    #   # => "the-config-yml-file"
+    #
+    #   slugify("The _config.yml file", "pretty")
+    #   # => "the-_config.yml-file"
+    #
+    # Returns the slugified string.
+    def slugify(string, mode=nil)
+      mode ||= 'default'
+      return nil if string.nil?
+
+      # Replace each character sequence with a hyphen
+      re = case mode
+      when 'raw'
+        Regexp.new('\\s+')
+      when 'default'
+        Regexp.new('[^[:alnum:]]+')
+      when 'pretty'
+        # "._~!$&'()+,;=@" is human readable (not URI-escaped) in URL
+        # and is allowed in both extN and NTFS.
+        Regexp.new("[^a-zA-Z0-9._~!$&'()+,;=@]+")
+      else
+        return string.downcase
       end
+
+      string.
+        # Strip according to the mode
+        gsub(re, '-').
+        # Remove leading/trailing hyphen
+        gsub(/^\-|\-$/i, '').
+        # Downcase
+        downcase
     end
 
   end
diff --git a/site/_docs/templates.md b/site/_docs/templates.md
index 12a70fc4..1b2877b2 100644
--- a/site/_docs/templates.md
+++ b/site/_docs/templates.md
@@ -212,11 +212,20 @@ common tasks easier.
     <tr>
       <td>
         <p class="name"><strong>Slugify</strong></p>
-        <p>Convert a string into a lowercase URL "slug" by replacing every sequence of spaces and non-alphanumeric characters with a hyphen.</p>
+        <p>Convert a string into a lowercase URL "slug". See below for options.</p>
       </td>
       <td class="align-center">
         <p>
-         <code class="filter">{% raw %}{{ page.title | slugify }}{% endraw %}</code>
+         <code class="filter">{% raw %}{{ "The _config.yml file" | slugify }}{% endraw %}</code>
+        </p>
+        <p>
+          <code class="output">the-config-yml-file</code>
+        </p>
+        <p>
+         <code class="filter">{% raw %}{{ "The _config.yml file" | slugify: 'pretty' }}{% endraw %}</code>
+        </p>
+        <p>
+          <code class="output">the-_config.yml-file</code>
         </p>
       </td>
     </tr>
@@ -252,6 +261,16 @@ common tasks easier.
 </table>
 </div>
 
+### Options for the `slugify` filter
+
+The `slugify` filter accepts an option, each specifying what to filter.
+The default is `default`. The are as follows (with what they filter):
+
+- `none`: no characters
+- `raw`: spaces
+- `default`: spaces and non-alphanumeric characters
+- `pretty`: spaces and non-alphanumeric characters except for `._~!$&'()+,;=@`
+
 ## Tags
 
 ### Includes
diff --git a/test/test_filters.rb b/test/test_filters.rb
index a8cd9737..0e18dc02 100644
--- a/test/test_filters.rb
+++ b/test/test_filters.rb
@@ -323,6 +323,10 @@ class TestFilters < Test::Unit::TestCase
       should "return a slugified string" do
         assert_equal "q-bert-says", @filter.slugify(" Q*bert says @!#?@!")
       end
+
+      should "return a slugified string with mode" do
+        assert_equal "q-bert-says-@!-@!", @filter.slugify(" Q*bert says @!#?@!", "pretty")
+      end
     end
 
     context "push filter" do
diff --git a/test/test_utils.rb b/test/test_utils.rb
index 6e643856..594281eb 100644
--- a/test/test_utils.rb
+++ b/test/test_utils.rb
@@ -144,6 +144,26 @@ class TestUtils < Test::Unit::TestCase
       Utils.slugify(title)
       assert_equal "Quick-start guide", title
     end
+
+    should "not change behaviour if mode is default" do
+      assert_equal "the-config-yml-file", Utils.slugify("The _config.yml file?", "default")
+    end
+
+    should "not change behaviour if mode is nil" do
+      assert_equal "the-config-yml-file", Utils.slugify("The _config.yml file?", nil)
+    end
+
+    should "not replace period and underscore if mode is pretty" do
+      assert_equal "the-_config.yml-file", Utils.slugify("The _config.yml file?", "pretty")
+    end
+
+    should "only replace whitespace if mode is raw" do
+      assert_equal "the-_config.yml-file?", Utils.slugify("The _config.yml file?", "raw")
+    end
+
+    should "return the given string if mode is none" do
+      assert_equal "the _config.yml file?", Utils.slugify("The _config.yml file?", "none")
+    end
   end
 
 end