You are seeing this because the project you were looking for has been archived. When projects are archived their data(downloads,source and website), is collected into a single tar.gz file.
ALF project. Archived: January 2009
CME project. Archived: January 2006
Corona project. Archived: April 2010
Cobol project. Archived: February 2010
Koi project. Archived: April 2006
Laszlo project. Archived: December 2006
Lepido project. Archived: June 2006
MDDi project. Archived: August 2008.
MDT EODM project. Archived: October 2008.
OMELET project. Archived: August 2005
Polinate project. Archived: December 2005
Scalamodules project. Archived: July 2010
Stellation project. Archived: June 2005