date_time_formats.rb

# from http://rpheath.com/posts/409-rails-time-date-formatting-with-lambda

# config/initializers/date_time_formats.rb
Time::DATE_FORMATS.merge!(
  :full => '%B %d, %Y at %I:%M %p',
  :md => '%m/%d',
  :mdy => '%m/%d/%y',
  :time => '%I:%M %p'
)

# Allows you to do Time.now.to_s(:full)
#
# Can also add logic using lambdas

Time::DATE_FORMATS.merge!(
  :friendly => lambda { |time|
    if time.year == Time.now.year
      time.strftime "%b #{time.day.ordinalize}"
    else
      time.strftime "%b #{time.day.ordinalize}, %Y"
    end
  }
)