Dan Brown, a blog reader, writes for Boxes and Arrows, an online magazine for information architects. His articles focus on tools and best practices for preparing information architecture deliverables. Dan has written some interesting articles on Visio recently, namely creating an annotation widget for wireframes, creating a shape that you can toggle (what we call a multi-shape), and how to represent content and data in wireframes. The site is chock-full of well-written articles, on information architecture generally and on using Visio to document information architecture specifically. Good stuff!
Mai-lan