Describe This
According to the announcement, Describe This is "a service designed for the automatic extraction of metadata from online resources. The site offers an easy to use interface where you can indicate the resource to analyze and how to download the results as XML, XHTML or RDF files." I tested it on my own website and on David Merrill's PDF (see below) and it worked for both, though certain desirable metadata (such as DC:creator) were missing. More...