Popular stencils
Swim Lane Deluxe
The swim lane diagram shows graphically the relationship of an application’s components and the group responsible for the component. This swim lane stencil includes Actors, Systems, Screens, Pages and Flow Diagram elements. Most of the stencil elements are borrowed from the existing Isometric stencils.
Rack Elements
A collection of frequently-used rack items, including the racks and rails themselves.
Simple Social Media Icons
A huge set of simple social media icons. They are vector / scalable. It's a direct port from Alex Peattie's set from here: http://www.alexpeattie.com/projects/justvector_icons. Thanks Alex!
Whale UX Wireframing Kit
Using custom XML shapes (included), this wireframing kit allows you to create complex forms and UI elements that act as a single shape. Includes pixel-optimized original icons and ideograms, buttons with glass effects and realistic Mac and Windows pointers.
Lean Six Sigma Tools
Continuous Process Improvement (CPI) tools for integrating into quality plans to include Define, Measure, Analyze, Improve, and Control (DMAIC) scientific model. Includes Bell Shaped Curve for plotting, Project Charter Matrix, Fishbone Diagram showing root causes, SIPOC Chart and Process Control Plan. Soon to come: Weighted...more
Twitter Bootstrap UI
This is a basic set of UI components to use when wireframing applications that use the Bootstrap framework. It is not a complete set, but it has already saved me tons of time and I'm hoping to add more in future versions soon.
Puzzle
Contains 21 puzzle shapes (all other combinations could be obtained with Rotation and Flip in Properties: Geometry).
Twitter Bootstrap 1.4 Assets & Grid
This is based on the Bootstrap CSS Toolkit 1.4 from Twitter (http://twitter.github.com/bootstrap/). Provides a 940px grid for laying out your mockups. Includes the design and layout assets.
Mobile - General
Cellphone stencil from the Design Stencil kit in the Yahoo! Design Pattern Library.