Apparently, there is a ten minute short film based on the "Cathedral," made in the Czech Republic.
This film by Robert Altman is not exactly a film version of "Cathedral," but rather a film based on various Carver stories. If you liked "Cathedral," you might like this movie, too.
An essay on Carver by Bright Lights, Big City author Jay McInerney, a former student of Carver's.
Two great interviews with Raymond Carver.
An essay discussing the similarities between "Cathedral" and the D.H. Lawrence story "The Blind Man."
Read this interview from 1978 to get a sense of Carver's poetry and prose.
He's got that dapper yet penetrating look down.
This is from 1988, the year of his death.
Just in case you were looking for a good timeline of Carver's life.
This links to lots of reliable sources for your Carver essays, including information about his life.