One of the greatest promises of modern UI frameworks is that they enable third party developers to build UI component libraries that can be traded on an open market. So far, Microsoft has probably done the best job with commercially viable component market places for Windows and ASP.Net components.
In the world of mobile apps, ready-made component libraries are probably even more crucial since modern mobile apps tend to connect to a large number of external services and are constantly innovating when it comes to UI and UX. The popularity of SDKs from Facebook, Twitter etc. proves this point. There are also a large number of open source mobile component projects on places like GitHub. But what about high quality commercial components / widgets for mobile apps? Enter Verious. It is setup to be a market place for mobile application components that covers all major mobile platforms including HTML5. Check it out!