Most of the first-generation mashups have been limited to the data freely available from governments, sites with APIs etc.; I can't wait to see what we'll get now that they can use Freebase. I can't wait to use it myself, for that matter. Best of all, those magical letters: "CC-BY".
Provides email addresses which redirect (POST) to a URL of your choosing.
Piggy Bank plugins are site-specific screen-scrapers that extract structured data as RDF, which can be analyzed, sorted and connected at your leisure, or shared through a "semantic bank".