damn.js

/* controller 1 */

app.userAuth.controller('LoginFormCtrl', ['$scope', 'UserData', function($scope, UserData) {
    $scope.email = UserData.email;
    $scope.password = UserData.password;
    $scope.login = function() {
        console.log('sent login form');
    }
}]);

/* controller 2. I want the emails to be two-way-bound */

.userAuth.controller('ResetFormCtrl', ['$scope', 'UserData', function($scope, UserData) {
    $scope.email = UserData.email;
    $scope.reset = function() {
        console.log('sent reset form');
    }
}]);

app.userAuth.factory('UserData', function() {
    var User = {
        email: null,
        password: null
    };

    return User;
});