UI Sketching software for Mac [closed]

Question

Is there any application for UI sketching on Mac OS X? Something like SketchFlow on Windows.

Answer 1

I really, really, really (you get the idea) love Balsamiq Mockups. It's cross-platform, via Adobe Air.

Answer 2

Omnigraffle is a very nice UI drafting system.

Extra stencils: http://graffletopia.com/

Answer 3

Balsamiq Mockups is cross-platform and is a very solid sketching program.