tail.js

var sys   = require('sys'),
    spawn  = require('child_process').spawn,
    http  = require('http');

http.createServer(function (request, response) {
  response.writeHead(200, {'Content-Type': 'text/plain'});
  var tail = spawn('tail', ['-f', '/var/log/system.log']);

  var kill_tail = function() {
    tail.kill();    
  }
  process.on('exit', kill_tail);

  request.connection.on('end', kill_tail);

  tail.stdout.on('data', function(data) {
    response.write(data);    
  });
}).listen(8124);