This article was written by a guy who created his web app without knowing Rails. In a few months, he had learned Rails, and had designed, developed and launched his own app. So don't be discouraged!

There's so many wonderful resources out there on UI/app development, but what I got from this article is that these lessons you'll learn best by creating (and using) web apps.

Here's the author's Rails article on the same site: http://sixrevisions.com/web-development/why-making-web-apps-...

The UI of your start-up very rarely makes or breaks it if you iterate and keep it clean. This is a great article about increasing user retention from x% to x+y%, but like A/B testing and everything else, it will not make a bad product good or a good product bad. Just keep moving forward and listening to your users, they'll tell you what they want and then once you have a customer B, you can A/B test to your heart's content.