lammert - 5:09 am on Feb 20, 2010 (gmt 0)
I don't use breadcrumbs on my sites because I think they don't fit the associative thinking process of visitors.
Breadcrumbs limit you to a hierarchical site structure with Homepage->Mainmenu->Submenu->Topic, which always takes two hops to jump from one topic to another. Instead I prefer topic based associative linking where every topic page has direct links to related topic pages on the same site. This not only increases usability for the user, but it also adds better link juice distribution throughout the site because link juice between related topic pages (the real spider food) is not distributed via menu pages, but directly from topic to topic. It is the same way that Wikipedia distributes link juice across its pages and looking at the number of Wikipedia pages at top positions in the SERPs the approach seems to work quite well.
The downside of associative linking vs. breadcrumbs is that it requires more manual work to setup.