Given example will demonstrate how to use multiple ng-app directives in a single page. Nothing is behind the wall, just bootstrap your model, controller.
<html>
<head>
<title>Multiple ng-app='' in angularJs by asptrics.net</title>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script>
</head>
<body>
<div id="div1" ng-app="">
<input type="text" ng-model="name" maxlength="240">
<span ng-bind="240- name.length + 'rem.'"></span>
</div>
<div id="div2" ng-app="myapp" >
<div ng-controller="mycontroller">
<input type="text" ng-model="name" >
<span ng-bind="name"></span>
</div>
</div>
<script>
var myapp = angular.module("myapp", [])
.controller("mycontroller", function($scope) {
$scope.name = "RajU";
});
angular.bootstrap(document.getElementById("div2"), ['myapp']); // initilize myaap module which is not binding by default.
</script>
</body>
</html>