Generate the schematics that can be inserted in the design documents.Perform usability testing before releasing the beta version.
Moqups is a nifty HTML5 App used to create wireframes, mockups or UI concepts, Using Balsamiq Mockups feels like you are drawing, but it's digital, so you can tweak and rearrange controls easily, and the end result is much cleaner. Is an online tool that makes it easy for you to create, link together, preview, and share mockups of your website or application.
It works on Linux, Windows and Mac and has a Firefox Extension It runs as either a Firefox plugin or in a standalone XUL runner. Open source and Free, the Pencil Project is a great tool for making diagrams and GUI prototyping that everyone can use.