This will need an xterm window ... and it's addicting to watch!

#!/usr/bin/perl
sub        sub{rand 39 /
999                 }sub O123
{                          printf
""                              ."\e[".
"%d"                                 . ";%d"
 .""                                      ."H%s"
  ,@_}                                       sub l234
   {O123                                          $|=1,1,
    "\e[J"                                          }while
       (1){                                              $c or
         do {                                               l234;
           $ u=&                                              sub;$
              v = &                                              sub
                ;$ c=                                            3999
                  ;$b=qw                                          /39
                     9 1 /[                                       int
                        rand 3]                                     };
                            O123 11*                              sin
                               ($v*$c)+                         13,
                                    39*cos($                u*$c)
                                         +41,qw+J A P H+[$c%4]
                                              ;($a++%$b)or$
                                                 c -- ;}