Q:

Does angular have a similar concept to ruby's module mixins?

I'd like to have a base factory (or service) from which other services share methods.
Is this possible in angular and if so, how?

A:

Working plunkr:
http://plnkr.co/edit/guObDjeLUYCEsp4omusX?p=preview
Read this:
https://javascriptweblog.wordpress.com/2011/05/31/a-fresh-look-at-javascript-mixins/
Factories and Services are just functions, so the same patterns in vanilla javascript are equally applicable.
app.controller('MainCtrl', function($scope, foobar) {
  $scope.name = 'World';
  $scope.fb = new foobar();
});

app.factory('foo', function() {
  var Foo = function() {};
  Foo.prototype = {
    doFoo: function(x) {
      return x + 3;
    }
  }
  return Foo;
});

app.factory('bar', function() {
  var Bar = function() {};
  Bar.prototype = {
    doBar: function(y) {
      return y * 2;
    }
  }
  return Bar;
});

app.factory('foobar', function(foo, bar) {
  var FooBar = function() {};
  angular.extend(FooBar.prototype, foo.prototype);
  angular.extend(FooBar.prototype, bar.prototype);

  // Anything else you want to do
  // ...

  return FooBar;
});

And a template:
  <body ng-controller="MainCtrl">
    <p>Hello {{name}}!</p>
    <p>Foo {{fb.doFoo(1)}}</p>
    <p>Bar {{fb.doBar(4)}}</p>
  </body>

