There are two interesting projects out there concerning linked data.
One is from Wikipedia called dbpedia. Essentially certain data from Wikipedia was extracted and then readied for use for searching and/or browsing. Right now, it looks like a very beta version. The example for the Lord of the Rings looked cool. However, for the common person trying to get some info on Tolkien’s book, it was not helpful. However, the potential to see connections between data that have not been seen before are very appealing. We will just have to wait until this gets off and going a little bit.
The second is called Silk from the Freie Universität. Like dbpedia, it is a discovery tool for data. The discovery is the new relationships that are found between data. This is on Google code. But again, this is very much for the techie to play around with.