I particularly like this quote, since it applies so emphatically to poster sessions:
I believe that most readers are looking for reasons to stop reading. Not because they’re malicious or aloof. They’re just being rational. If readers have other demands on their time, why should they pay any more attenion than they absolutely must? Readers are always looking for the exit.
Most of the website deals with smaller details needed for multi-page documents, rather than more complex layout of multiple parts on a single that is the problem for most poster makers. But there is good advice on how wide columns should be (two to three alphabets should fit in a single line), and tips on page layout, including this gem:
Don’t try to resolve typographic decisions with logic.
The book is significantly longer than the website, but the website is helpful.