Interesting and/or useful linked data - what do you know of?

For both the GLD deliverables and for our own edification and promotion of GLD, I am eliciting pointers and recommendations for "Interesting and/or useful linked data" or even data that could become lined data.  Of particular interest to me is data that can be federated with other data and used with analytics to support decision making, collaboration or other business processes.

Many of the GLD demos I have seen are of such a closed data source that it is not easy to see the leverage GLD is providing - it looks like any web application.  Data is more valuable when rubbed together, to show this effectively we need the data.  One of my interests is semantic federation, use cases for where this would be of benefit are also interesting.  Of course other data or use cases may be suggested - this is a mostly open enquiry.

Some of this data and/or its schema may also be applicable to the GLD vocabulary deliverables, highlighting such data and schema would be appreciated.  Schema can be listed on the wiki: http://www.w3.org/2011/gld/wiki/Vocabulary_Discussion_Summary

So, what is out there? What is cool?



-Cory Casanave