Okay, maybe my method does take a little extra work to translate, but this is how I do it.
Post-it notes on the wall make a flexible sitemapping system that multiple people can stop by, contemplate, and make changes to as they wish as long as you leave it up.
I work on PC’s, so I don’t have access to some of the cool sitemapping tools that Mac users can try. Adobe GoLive does have sitemapping built in; I’ve taken a brief look but have not yet used it. Generally I wind up translating my post-it sitemap into InDesign using a template that I’ve developed over time.
But the post-it note way is so easy and is a good way to nail it all down before you have to start moving all those little flowchart symbols and lines all over the place.