I'm a huge fan of visualization tools, particularly for social networking and similar applications. Tools like i2 Analyst Notebook and ClearForest's ClearResearch provide insights into huge volumes of information for the professional user. Grokker and Vivisimo provide similar benefits in the web search world. The tools Rubel shows are not at that level, but each does an interesting job of showing the network of links around a given blog or website.
Of the two, Touchgraph is the more useful one. Links between sites are color-coded to make it easy to see inbound or outbound links.
More visually appealing, but with less functionality, is this map by Sala Aharef's Websites as Graphs. It helps you see the density of a network, with color-coded indications of links, images and more, but is not very navigable.
As users struggle to deal with information overload, data visualization will start to take hold among mainstream users. In the meantime, we can admire the creativity of the early offerings.