All websites should start with a good plan. Focussing on the design process first may be common for smaller sites. For larger sites, when user experience is paramount, creating an initial sitemap or user flow map is an effective way.
An article about how video game UIs could influence web designers. Although not relevant to my current brief it still has a lot of information about user interface in games. Such as menu flow, icons, loading screens and tabbed menus.
Merlin is a modular synthesis environment for the iPad, allowing artists to create sounds with a visual, node-based patching interface. These are mockup screenshots as a proof of concept, so you won't find this in the App Store—but maybe s.