Moved plugins to root directory. I'm ditching the idea of shipping plugins with themes until it's more obviously necessary. This way it's easier to merge and update plugins.

plugins/custom_filters.rb

@@ -0,0 +1,75 @@
+#custom filters for Octopress
+
+module OctopressFilters
+  # Used on the blog index to split posts on the <!--more--> marker
+  def exerpt(input)
+    if input.index(/<!--\s*more\s*-->/i)
+      input.split(/<!--\s*more\s*-->/i)[0]
+    else
+      input
+    end
+  end
+
+  # Summary is used on the Archive pages to return the first block of content from a post.
+  def summary(input)
+    if input.index(/\n\n/)
+      input.split(/\n\n/)[0]
+    else
+      input
+    end
+  end
+
+  # Replaces relative urls with full urls
+  def full_urls(input, 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)
+    input.gsub /(https?:\/\/)(\S+)/ do
+      $2
+    end
+  end
+
+  # replaces primes with smartquotes using RubyPants
+  def smart_quotes(input)
+    require 'rubypants'
+    RubyPants.new(input).to_html
+  end
+
+  # Returns a title cased string based on John Gruber's title case http://daringfireball.net/2008/08/title_case_update
+  def titlecase(input)
+    input.titlecase
+  end
+
+  # Returns a datetime if the input is a string
+  def datetime(date)
+    if date.class == String
+      date = Time.parse(date)
+    end
+    date
+  end
+
+  # Returns an ordidinal date eg July 22 2007 -> July 22nd 2007
+  def ordinalize(date)
+    date = datetime(date)
+    "#{date.strftime('%b')} #{ordinal(date.strftime('%e').to_i)}, #{date.strftime('%Y')}"
+  end
+
+  # Returns an ordinal number. 13 -> 13th, 21 -> 21st etc.
+  def ordinal(number)
+    if (11..13).include?(number.to_i % 100)
+      "#{number}<span>th</span>"
+    else
+      case number.to_i % 10
+      when 1; "#{number}<span>st</span>"
+      when 2; "#{number}<span>nd</span>"
+      when 3; "#{number}<span>rd</span>"
+      else    "#{number}<span>th</span>"
+      end
+    end
+  end
+end
+Liquid::Template.register_filter OctopressFilters