Regarding the entry about infinite categories. I agree with the main idea and have actually implemented Simpy (see http://www.simpy.com/) the same way. Users add keywords or tags to bookmark/link entries, and each of those keywords or tags becomes a 'category'.

Imagine a pile of something, and each tag or keyword allows you to get a nice, focused, vertical slice of that pile, retrieving only the stuff you are interested in. Because each bookmark/link entry can be associated with multiple tags or keywords, each entry can really belong to an infinite number of 'categories' (vertical slices).

It's a much more flexible and faster way of organizing and finding information, Give it a try, and you'll abandon your hierarchical bookmarks/favorites in the next 24 hours. That is to say, if you even use bookmarks. I don't blame you if you don't use them – they are a pain to use inside browsers, but with services like Simpy they actually quickly become a rich personal information resource, much more personal than Google, for instance.