<p>Sure, we can use a simple bulleted list or a mindmap.  But, there must be a better, more interactive way.  What do you use when starting your website architecture?</p>

By "architecture", do you mean the initial site map? If not, please post a clarification and I'll edit my response.
Our tech team starts development after our creative department has done their stuff. Part of what we get is output from the information architect. He passes off a graphical sitemap, a detailed sitemap as an Excel sheet, and a set of wireframes in a PDF.