forever.rb

trap("INT") { $done = true }

class Forever

  def every(timespan, &block)
    @threads ||= []

    thread = Thread.new do 
      last_run = 0
      while !$done
        now = Time.now.to_i
        if now - last_run > timespan
          block.call  
          last_run = now
        end
        sleep 1
      end
    end

    @threads.push(thread)
  end

  def run
    @threads.collect(&:join)
  end

end

require 'rubygems'
require 'active_support/all'

forever = Forever.new
forever.every 5.seconds do
  puts 'still running'
end 

forever.run