Completely decoupled IIFE (immediately-invoked function expressions) which are able to talk to each other without introducing any global variables.

core.js

(function (win, doc, undefined) {

	var modules = Object.create(null),
		moduleContext = {
			sayHi: function () { console.log('HI from module'); }
		},
		handleRegisterModuleEvent = function handleRegisterModuleEvent(event) {
			core.registerModule(event.module);
		},
		core = {
			init: function () {
				doc.addEventListener('registerModule', handleRegisterModuleEvent, false);
				console.log('core initalized');
			},
			destroy: function () {
				doc.removeEventListener('registerModule', handleRegisterModuleEvent, false);
				console.log('core destroyed');
			},
			getContext: function () {
				var context = Object.create(moduleContext);
				context.additionalFoo = 'bar'; // just to demonstrate that the context could be modified before it get's returned
				return Object.freeze(context);
			},
			registerModule: function (module) {
				modules[module.name] = module(this.getContext());
				console.log('module: ' + module.name + ' successfully registered.');
				this.startModule(module.name); // in reality this call shouldn't be placed here, but to demonstrate the startup of a module i just wrote it to the registerModule method.
			},
			getModule: function (moduleName) {
				return modules[moduleName];
			},
			startModule: function (moduleName) {
				try {
					console.log('starting module: ' + moduleName);
					this.getModule(moduleName).start();
				} catch (e) {
					console.error("can't start module: " + moduleName + ' - ' + e);
				}
			},
			stopModule: function (moduleName) {
				try {
					console.log('stopping module: ' + moduleName);
					this.getModule(moduleName).stop();
				} catch (e) {
					console.error("can't stop module: " + moduleName + ' - ' + e);
				}
			}
		};

	core.init();

}(window, document));

myCoolModule.js

(function (win, doc, undefined) {
	var registerModule = doc.createEvent('Event');
	registerModule.initEvent('registerModule', false, false);

	registerModule.module = function myCoolModule(context) {
		return {
			start: function () {
				console.log('myCoolModule started!');
				this.speak();
				console.log('context: ', context);
			},
			stop: function () {
				console.log('myCoolModule stopped!');
			},
			doFoo: function (foo) { console.log('done: ' + foo); },
			speak: function () {
				context.sayHi();
			}
		};
	};

	doc.dispatchEvent(registerModule);

}(window, document));