DENIM - An Informal Tool For Early Stage Web Site and UI Design
DENIM is a system that helps web site designers in the early stages of design. DENIM supports sketching input, allows design at different refinement levels, and unifies the levels through zooming.
I found this tool while I wanted to create a small sketch of an idea I have for a new site (Visio was hardly good), after couple of minutes of usage (without any Pen) I can say that it is a very nice idea but a little hard to manage and I would suggest to buy a Pen to ease the design process.
At the end I went back a painted what I wanted on a piece of paper <smile />