The folks at Relative Wave are creators. They're making it easier for software developers to see what their apps will look and act like before they create a final design. With their tools, creators can visualize what they're making for a smartphone ON the smartphone, rather than on a PC. When you edit something in their system, "Flow", you see it change in real-time on the smartphone you're prototyping on. Google just acquired this company, and they've made their software free for download for Mac users in the process.