One more reason to buy an Apple is Pathway: This program helps to navigate through Wikipedia in a bit more structured way. It visualises pathways through wikipedia and proposes interesting links to other wiki pages. After a while navigating through wikipedia users normally find themselves “totally lost in myriads of loosely related pages. What I needed, was an application that could easily archive the path I follow through Wikipedia pages”, says the author of Pathway.
Thanks to Thomas Fundneider for pointing that out!
About the Social Semantic Web 