Mockup / Wireframe / Prototype Tools

Balsamiq “Mockups”

• demo video
• Adobe AIR based licensed$$ desktop version – very full featured
• Web based demo - works well for quick thoughts

Pencil

• free
• Cross platform desktop app
• Sketchy stencil for the “low fidelity” look

Gliffy

• free basic web functionality
• $$ubscription model for featured version

SketchFlow is apparently coming back to VS2012 – Microsoft seems to be in a bit of a tizzy buttoning down all the loose ends in the latest transition to all things immersive.
Infragistics has Indigo Studio
There’s tons more out there… prototyping is apparently a very hot item