I am very inspired by websites like imgur, dropbox, screencloud, maybe w3schools...you get my point. Fresh web-services with some new idea, not big portals but something simple yet useful and used by many people, something simple and new.
What aspects of my developer career should I focus to be able to build such things on my own if I have enough ideas? (Sure if it ends up being popular I can get more developers to help me and so on, but at first I can do it alone, right?)
I am currently a PHP web-developer, I know HTML+CSS+JS+AJAX+JQuery. But even like that there still is web-design, there are a lot of paths: websites for enterprise, startups, webservices, entertainment websites and serious bank/document flow systems, frameworks used for big systems, different approaches for little ones, etcetcetc. Which path should I take to be able to start my own projects like the ones that I listed on top which inspire me?