I've enjoyed the toys TouchGraph provides for many years. Here is another that I'm just now exploring after getting lots of noise at the beginning of September. Matt Hodgson pointed to the Touchgraph Google Browser, which describes itself thusly:
The TouchGraph Google Browser reveals the network of connectivity between websites, as reported by Google's database of related sites.
So, if you put in a phrase, it will group the results by relatedness. And if you do an ego search, it does the same thing, which is what I've done with the attached image (click to see it in living color). Each node in the network can be explored again by clicking to have the browser extend the search depth for that website / webpage. So, you can explore all the edges of a network, or you can dive deeper into one of the nodes. I like how it groups similar nodes by color. And as you expand networks, it picks new colors for new groupings.
They also have a Facebook Browser (similar to the Google browser) and an Amazon Browser (purchase and recommendation patterns).