UX Flow Wireframe Prototyping System - Create beautiful user flows prototypes for your next project
Xcode - Xcode is Apple’s powerful integrated development environment for creating great apps for Mac, iPhone, and iPad. Xcode 4 includes the Xcode IDE, instruments, iOS Simulator, and the latest Mac OS X and iOS SDKs.
draw.io - Online diagramming application
Angle 2 Mockups - A giant Sketch Library for creating app presentations
UMLGraph - UMLGraph is a professional automated drawing tool that allows the designers the declarative specification and drawing of UML class and sequence diagram.
Balsamiq Mockups 3 - New public beta for the popular prototyping tool