We started this book by learning a technique called paper prototyping. For your own work with clients, it's a great tool. However, if you're dealing with larger or distributed teams, you might need something more. Balsamiq (http://www.balsamiq.com/) is a very popular UX tool for rapid prototyping. It is perfect for creating and sharing interactive mockups.
And when I say very popular, I mean lots of major names that you're used to seeing. Over 80,000 companies create their software with the help of Balsamiq Mockups.
So, let's take a look at what the creators of Flood.FM had in mind. Here is the first screen they drew; it looks like a pretty standard implementation so far. It has an icon toolbar at the bottom and a listview in the content. Translating that is pretty simple, really. We've done this before using Glyphish icons and standard toolbars.
Ideally, we'd like to keep this particular implementation as pure HTML/JS/CSS. That way, we could compile it into a native app...