gistfile1.js

var _spawn = require('child_process').spawn,
    children = [];

function spawn() {
  var id = children.push(_spawn.apply(null, arguments)) - 1;
  children[id].on('exit', function() {
    delete children[id];
  });

  // If you want to pipe stuff...
  children[id].stdout.pipe(process.stdout);
  children[id].stderr.pipe(process.stderr);
}

function cleanup() {
  children.forEach(function(child) {
    child.kill('SIGINT');
  });
}

spawn('echo', [ 'Test' ]);
cleanup();