This article is from 2005. Technologies and best practices have evolved since then.
There's a new feature over at del.icio.us. You can bundle your tags now. That makes it much easier for you to sort your bookmarks.
http://del.icio.us/settings/YOURUSERID/bundle this lets you assign tags to "bundles" which will cause the tag listing on the right to be organized by the specified bundles.