Web Site Mock-ups and StoryBoarding?

brado77 asks: "I have spent years on the programming side of web development, but am presently moving into more of a design interest and focus. I am interested in what design tools out there for web site mock-ups and storyboarding that people find the most effective and fastest. No matter how skilled, programming is generally both too slow a method for this, and aesthetically clumsy (mucking through HTML to quickly change colors, layout, fonts, etc.). Photoshop is another route, but addresses its content from a structural perspective different from web layout. Has anyone found any tools specifically for mock-ups and storyboarding that are geared toward design professionals? (I can already sense the onslaught of "pencil and paper" and "whiteboard and marker" responses... :-)"