#include <fcgi_stdio.h>

    void main(void)
    {
        int count = 0;
        while(FCGI_Accept() >= 0) {
            printf("Content-type: text/html\r\n");
            printf("\r\n");
            printf("Hello world!<br>\r\n");
            printf("Request number %d.", count++);
        }
        exit(0);
    }

[root@localhost lighttpd]# CFLAGS="-lfcgi" make tiny

[root@localhost lighttpd]# /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf
2006-07-29 23:00:13: (mod_fastcgi.c.863) child exited (is this a FastCGI binary ?): 255 
2006-07-29 23:00:13: (mod_fastcgi.c.1138) [ERROR]: spawning fcgi failed. 
2006-07-29 23:00:13: (server.c.621) Configuration of plugins failed. Going down. 

my configuration, ....

fastcgi.server = ( "tiny" =>
  ((
     "socket" => "/srv/www/lighttpd/tiny.socket",
     "bin-path" => "/srv/www/lighttpd/tiny"  #,
    # "min-procs" => 1,
    # "max-procs" => 32,
    # "max-load-per-proc" => 4,
    # "idle-timeout" => 20 
  ))
 )