Using gravatar in rails. Taken from http://stackoverflow.com/questions/770876/how-do-i-add-gravatar-identicons-into-ruby-on-rails

gravatar.rb

def gravatar_for email, options = {}
  options = {:alt => 'avatar', :class => 'avatar', :size => 80}.merge! options
  id = Digest::MD5::hexdigest email.strip.downcase
  url = 'http://www.gravatar.com/avatar/' + id + '.jpg?s=' + options[:size].to_s
  options.delete :size
  image_tag url, options
end

# Using identicons etc through gravatar (see http://en.gravatar.com/site/implement/images/)
id = Digest::MD5::hexdigest email.strip.downcase
url = 'http://www.gravatar.com/avatar/' + id + '.jpg?f=y&d=wavatar'   # wavatar
url = 'http://www.gravatar.com/avatar/' + id + '.jpg?f=y&d=identicon' # identicon
url = 'http://www.gravatar.com/avatar/' + id + '.jpg?f=y&d=monsterid' # monsterid