Rich Little's Christmas Carol is another favorite.  It is a 1978 Canadian TV special, shot on videotape, but it has aired here on HBO.  It's a one-man show, in which Little enacts the Dickens tale through a variety of amusing impersonations.
 
Scrooge - W.C. Fields
 
Bob Cratchit - Paul Lynde
 
Fred - Johnny Carson
 
Solicitor - Stan Laurel
 
Solicitor - Oliver Hardy
 
Jacob Marley - Richard Nixon (instead of chains, he is covered in spools of audiotape)
 
Ghost of Christmas Past - Humphrey Bogart
 
Ghost of Christmas Present - Peter Falk as Columbo
 
Ghost of Christmas Future - Peter Sellers as Inspector Clouseau
 
Fezziwig - Groucho Marx
 
Dick Wilkins - James Stewart
 
Mrs. Cratchit - Jean Stapleton as Edith Bunker
 
Tiny Tim - Truman Capote
 
Businessman - John Wayne
 
Businessman - George Burns
 
Businessman - James Mason
 
Boy - Jack Benny
 
The special is available on DVD.
 
My all-time favorite version of A Christmas Carol is the 1970 musical adaptation, Scrooge, directed by Ronald Neame, and starring Albert Finney.  The film is very close to the Dickens novella, and has a nice atmosphere.  At times, it's even rather macabre and frightening, with a few sequences added that weren't in the original story, such as a ghostly coachman riding through Scrooge's home, prior to his first meeting with Marley, and the sequence set in the future, at Scrooge's death, where he falls into his grave, and meets up with Marley again, in the other place, where Scrooge is forced into a fate similiar to Marley's.  This sequence is usually cut out of TV broadcasts of the film, but is included in its entirety on the DVD.  Alec Guinness makes a spooky Marley, and the cast, made up of British stage and film actors, is excellent.
 
The score is by famed composer Leslie Bricusse.