Freebase: O'Reilly's right. Its addictive!
Tim O'Reilly said it and I'm going to repeat it now that I've gotten the chance to see what he's talking about: Freebase is addictive. I spent quite a bit of time messing around with it yesterday. When you start using it, you begin to feel the power of it.
Why does it feel so powerful? Because as you are typing in information, you realize that the information is linking to objects, and the information becomes very useful. It is not like posting Wikipedia articles, where the information is only seen by humans. In Freebase, the computer can use the information in powerful ways. So when you say that the "American Civil War" is a historical event (a type that I made), the computer knows that the American Civil War has a starting date and an ending date (and any other information associated with a "historical event"). Then this same information can be used in a web app. For example, a web app could be made that shows a timeline and a map. For any given location or area of the map, the user could see all the historical events that happened there in a given time range. The user could scroll back and forth through the timeline to see all the different historical events in the given location or area on the map. This kind of thing would be easy to do with Freebase. I don't know if this sounds exciting to anybody other than developers but to a developer like me who can use Freebase's free API in his web app, this is quite exciting. All of a sudden, a lot of new opportunities for powerful functionality are enabled.
If anybody wants an invite, see this post.