GEDCOM Search Engine - Upload a GEDCOM file, get a list back of other researchers with similar lines.
Relationship links for genealogical data - <link rel="alternate"> type tags are often embedded in blog pages to inidcate alternative representations of that blog, usually in the form of an RSS or Atom feed. Why aren't genealogical sites using these kind of links to point to genealogical data in GEDCOM or XML format?
The Big Problems - What are the big problems we face in genealogical research today?