Put each of these in ~/.irbrc

Configure IRB's prompt for a Rails app

if defined? Rails
  # Customize the IRB prompt.

  short_env = case Rails.env
    when 'development'
      'dev'
    when 'production'
      'prod'
    else
      Rails.env
    end

  # :PROMPT_I  Normal prompt
  # :PROMPT_S  Prompt when continuing a string
  # :PROMPT_C  Prompt when continuing a statement
  # :PROMPT_N  Prompt when indenting code
  # :RETURN    String that prefixes output of a statement. This is passed to Kernel#printf .
  IRB.conf[:PROMPT] ||= {}
  IRB.conf[:PROMPT][:RAILS] = {
    :PROMPT_I  => "#{Rails.application.class.parent_name} #{short_env} > ",
    :PROMPT_S  => "#{Rails.application.class.parent_name} #{short_env} %l> ",
    :PROMPT_C  => "#{Rails.application.class.parent_name} #{short_env} > ",
    :PROMPT_N  => "#{Rails.application.class.parent_name} #{short_env} ..  ",
    :RETURN    => "=> %s\n",
  }

  IRB.conf[:PROMPT_MODE] = :RAILS
end

Configures IRB's prompt.

# Configure the prompt.
#
# This changes it from
#   1.9.3p327 :001 >
# to
#   >>
IRB.conf[:PROMPT_MODE] = :SIMPLE

Find methods inside an object easily.

# Easily print methods local to an object's class. E.g.
#   p = Product.first
#   p.local_methods
#   p.methods_matching /price/
#
class Object
  def local_methods
    (methods - Object.instance_methods).sort
  end

  def methods_matching(pattern)
    methods.select {|m| m.to_s.match pattern}.sort
  end
end