Adonit's Forge is a design app for iPads that is optimized for visual brainstorming, especially in groups.
Whether you're drawing with a stylus or a finger, the app provides tons of options to get your creativity flowing freely. After a digital drawing is created, the app provides a handy place for collections of drawings to be set out and viewed as a whole or arranged into piles. Rather than having a drawing that will be stuck on a tablet, the app also provides a way for users to export drawings to Dropbox for further refinement. This is a great way for a group of two or more people to create, organize and view drawings from their own personal devices, as well as collaborate on the fly as needed.