contact.rb

class Contact < Tableless
  column :email,   :string
  column :message, :text

  validates_presence_of :email, :message
end

tableless.rb

class Tableless < ActiveRecord::Base
  def self.columns()
    @columns ||= []
  end

  def self.column(name, sql_type = nil, default = nil, null = true)
    columns << ActiveRecord::ConnectionAdapters::Column.new(name.to_s, default, sql_type.to_s, null)
  end

  # override the save method to prevent exceptions.
  def save(validate = true)
    validate ? valid? : true
  end
end