I'm looking for a piece of software that will enable me to visually design the flow of a website. I'm not looking for something to use to code html or php, just be able to give me an overview of how the site will hang 'together' - a sort of website flowchart.
It doesn't have to be flash or anything - just easy to use. The closest thing I can think of is a kind of 'Visio for web sites', allowing me to drag and drop pages, linking them with arrows etc.
I know I could use a whiteboard or I've heard of people using post-it notes but I'm looking for something in an electronic format.