Example of a gravatar helper method for Rails (3)

users_helper.rb

# Assumes two things
# i)  Your user class's to_s method outputs something useful - perhaps their name or email address
# ii) Your user class has an 'email' attribute
#
# This will work with any ruby class, it doesn't have to be an activerecord model
#
# usage: gravatar_tag(my_user, size: '32x32', alt: 'This is the alt text', title: 'Any other options get passed into image_tag')

module UsersHelper

  def gravatar_tag(user, image_options = {})
    image_options[:size] ||= '80x80'
    image_options[:alt]  ||= image_options.delete(:alt) || user.to_s

    pre_hash  = user.email.strip.downcase
    post_hash = Digest::MD5.hexdigest(pre_hash)

    base_url = request.ssl? ? 'https://secure.gravatar.com' : 'http://www.gravatar.com'
    url = "#{base_url}/avatar/#{post_hash}?s=#{image_options[:size].to_i}"

    image_tag url, image_options
  end
end