As Wikis reflect the non-hierarchical, neuronal network-style most of us think, Wikis tend to evolve into non-hierarchical, neuronal-network-style information pools that consist of many, interlinked Wiki pages that can be hard to navigate.
Some problems like orphaned pages, duplicate content, missing categorization, bad navigation can be overcome with the help of technology like powerful search, tagging or "related content" pages, in the end it comes down to human knowledge and understanding to make a Wiki an exceptional knowledge base.
People who love to organize Wikis by