What is the coolest thing you can do in ten lines of code?(stackoverflow.com)

  CLI     ; Disable interrupts
  HLT     ; Halt CPU until next interrupt

  ] CALL -151
  * 300: AD 30 CO 20 ED FD 4C 00 03
  * 300G

    ;; run this on SBCL
    (sb-ext:unlock-package :common-lisp)
    (let (syms) (do-symbols (s :common-lisp) (if (fboundp s) (push s syms)))
      (labels ((worm (sym)
    	     (let ((next (elt syms (random (length syms))))
    		   (old (symbol-function sym)))
    	       (format t "~%Worm attacks ~a, next target is ~a!~%" sym next)
    	       (setf (symbol-function sym)
    		     (lambda (&rest args) 
    		       (when next (worm next) (setf next nil)) (apply old args))))))
      (worm '+)))
    ;; now try adding some numbers (and so on)

    let bits = Bitstring.bitstring_of_file "data" in
    bitmatch bits with
    | { width : 5;
        data : width } ->
        printf "width %d data %Ld\n" width data

  : z^2 2dup z* ;
  : layer push push z^2 pop pop 2dup push push z+ pop pop ;
  : many layer layer layer layer layer layer layer layer layer layer ;
  : len dup * swap dup * + ;
  : mant y 0.7 - 3 * x 0.5 - 3 * many drop drop len dup 1 < * ;
  0 0 mant
  0.1 0.1 mant
  0.2 0.2 mant

    for k in [pow(x,37,0x13AC59F3ECAC3127065A9) for x in [0x195A0BCE1C2F0310B43C,
    0x73A0CE584254AB23D5A0, 0x12878657EA814421CC92, 0x7373445BB3DA69996F4A,
    0x77A7ED5BC3AA700E80B2, 0xE9C71C94ED87ADCF7367, 0xFE920395F414C1A5DB50]]:
    print "".join([chr(32+3*((k>>x)&1))for x in range(79)]) # <anakin at pobox.com>

    #include <math.h> /* outputs 8 kHz 8-bit unsigned pcm to stdout */
    main(v,i,z,n,u,t){for(v=-1;;)for(n=pow(/* gcc -lm sig.c;./a.out>/dev/dsp */
    1.06,"`cW`g[`cgcg[eYcb^bV^eW^be^bVecb^"[++v&31]+(v&64)/21),i=9 99;i;putchar(
    128+((8191&u)>i?0:i/8)-((8191&(z+=n))*i-->>16)))u+=v&1?t/2: (t=v&6?t:n/4);}

    iterate (\xs -> zipWith xor ([0] ++ xs) (xs ++ [0])) [1]

  function Y(f)
    local function g(...) return f(g,...) end
    return g
  end

  print(Y(function(rec,x)
            if x < 2 then
              return 1
            else
              return x * rec(x-1)
            end
           end)(5))