I'm putting a few pages in XML on my website and linking to them from here to see if and how Google adds them to its index. Each has a hopefully unique phrase to make it easier to search for: pomegranate Xerox capybara.
The pages:
RSS file that links to another, xmlgoog2a.xml. Only xmlgoog2.rss links to that one.
DocBook file that doesn't mention DocBook.
DocBook file that does, and uses ulink to link to another.
arbitrary XML file that has an a/@href link to another.
arbitrary XML file with a namespace URI.
arbitrary XML file with an arbitrary link element with a "url" attribute.
arbitrary RDF/XML file with an rdf:resource attribute pointing at another file.
XHTML file with head/link link to another document. It links to others as well; see 9a, 9b, 9c.
XHTML file with links testing use of src attribute for linking. See 10a, 10b, 10c, and 10c-1.