inVision is an awesome web application that is great for prototyping and getting your head around a user-experience and navigation. You can also present your designs to clients, within a web browser, without touching any code.
Just drop all of your image files (.jpg .png .pdf) into a folder similar to Dropbox,and then view them in the inVision App. From here you can add your hotspots and replicate a ‘working’ site, great for demonstrating the navigation to a client.
It’s perfect for designers that use Adobe Fireworks for interface design. Simply place your working .png files in the inVision folder, and they will continually update to the live preview.
You and your collaborators can add comments to the design. These comments are also emailed to you so you don’t miss a thing.
It’s a quick and pwerful tool that will allow you to plan out a site before touching any code.