Mash up derby
At Wikipediavision you can watch as people around the world make updates to Wikipedia. Each notice includes a link to the subject where you can see what was just updated.
The concept is based on Flickrvision, where you can see new pictures as they are uploaded to the photo-sharing site. Pretty addictive.
These are both examples of Mashups. A mashup is when people take more than one application and mix them together. (Google Maps with Wikipedia and Flickr respectively in these cases).
Other examples of mashups include WeatherBonk, Pageflakes and the Wheel of Lunch.