Destination: Argleton! Visiting an imaginary place. A fake town in Google Maps.
The TouchGraph GoogleBrowser uses Google's related: links to visualize local maps of the web. Enter www.metafilter.com and watch the spider unfurl its arms. Click on "Show Singles" for more specific pages, or set the "radius" to 10 for more nodes. (Full instructions are here. ) Requires something called the Java Virtual Machine and may be IE-only, but that doesn't matter: my neighbors just called to ask if I was going to keep whooping like that all night.
The ThreeRing Web Mapping project adds a dot to a blank canvas showing your geographic location (or that of your ISP, as best it can guess based on your IP address). They've also got a code snippet to put on your own site that automagically adds your visitors to the map. The US is already clearly defined, Europe is getting there, and Oceania is coming into view. (They've also got one of them Tag-Board thingies, which is painful to read for any length of time.)