Sure. You know how simple this task is when you have an event loop, right? Here, I'll write a port scanner right now:

  class HostProbe 
    module Probe
      attr_accessor :bp
      def connection_completed
        @win = true
      end

      def unbind
        self.bp.closed(self, @win)
      end
    end

    def closed(obj, won) 
      @inflight_now -= 1
      port = @inflight_q.delete(obj)
      if won                 
        puts "%TARGET-LISTENING: #{ @target }:#{ port }"
      end
      fill()
    end

    def sweep
      Generator.new do |g|
        (1..65535).each {|port| g.yield port}
      end
    end

    def fill
      @inflight_now.upto(@inflight_max) {
        @inflight_now += 1
        if(port = @sweep.next) 
          EventMachine::connect(@target, port, Probe) do |c|
            c.bp = self
            @inflight_q[c] = port
          end
        end 
      }
    end

    def initialize(host, opts={}) 
      @target = host
      @sweep = sweep
      @inflight_q = {}
      @inflight_now = 0
      @inflight_max = opts[:inflight_max] || 10
      fill()
    end
  end

  EventMachine::run { 
    HostProbe.new(ARGV[0])
  }

I think that may be it? I'm not even going to bother seeing if it evaluates. I write that stupid script once a month or so. There is probably a set of nmap options that crushes it for speed, but with the default options and a firewalled target network (ie: most professional nmap targets), I lap nmap with it.