Mokkup - Create Stunning Dashboard Mocks in Minutes!
Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
Moqups - The most stunning HTML5 app for creating resolution-independent SVG mockups, wireframes & interactive prototypes for your next project
MockFlow - A super easy wireframing tool with all the other tools you need in the product design process
Invision - Prototyping and collaboration for design teams
UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.