The freshest commentary on memorable endings that I found was on the NPR "Day to Day" web site and its related blog—that's probably because the show ends today and for the last few days they've been discussing endings there. One segment, A Critic's Favorite Final Episodes, discusses three memorable endings: from "Six Feet Under," "The Sopranos," and "Seinfeld." A related blog post, Final Episodes by Jason DeRose, provides footage to the last moments of the shows discussed. Again, "Six Feet Under" is listed among the favorites.
I also would list "Six Feet Under" among my favorite TV show endings—those brilliant last six minutes helped me forgive the screenwriters for the preposterous/maudlin storylines from its last two seasons. (However, if you watch it via the link above, you're probably not going to find it very affecting unless you've watched the show and are familiar with the characters and the fact that each one of the 63 shows in the series began with a death). After I saw it the first time, I rewound it and watched it over and over—the daughter driving through the California desert while each of the main characters lives' are summed up in moments of film was wrenchingly beautiful to me.
I applaud those writers/screenwriters who can create an ending that's innovative, especially when it offers a fitting conclusion and isn't just there to shock or dismay its viewers. Among the latter, I'd include "Twin Peaks," when Agent Cooper becomes Bob; the "Colbys," where Fallon is stranded on a highway and abducted by aliens; and "The Prisoner," where he lifts a mask off a man's face to find himself, and then he drives away... unless he's driving towards the same fate over and over.
In the fresh, creatively appropriate category I'd include "Seinfeld," "St. Elsewhere," and "Newhart" (which I admit I never watched except for those much-acclaimed last few minutes).
Of course, perhaps my list would be longer if I had premium cable—I've never watched "The Sopranos" and am currently, slowly making my way through "The Wire" on DVD via Netflix—and if I watched any kind of TV on a regular basis.
In a future post, I hope to look at both cliched and memorable endings—and beginnings—of fictional works.