Movie: Citizen Kane, Pulp Fiction, Akira (Anime; expanded it, Otomo should have), Ghost in the Shell (Anime), Shawshank Redemption, Scarface (he got what was coming to him), Goodfellas, Reservoir Dogs, Snatch (Best fight movie), Fight Club, Click, and Yojimbo and Fistful of Dollars.
Manga: Akira, Ghost in the Shell, Dragon Ball Z, Death-Note (not the perfect ending but ended decently.), Domu: A Child's Dream, and Gantz Neon Genesis Evangelion.
Anime: Akira, Ghost in the Shell Stand Alone Complex 1 and 2, and that is all I can think of right now.
Books: Atlas Shrugged, Tom Sawyer, Crime and Punishment, Huck Finn, The Fountainhead, Great Gatsby, Grapes of Wrath, 1984, Brave New World.
Comic Books: 100 Bullets, Watchmen, V for Vendetta, The Avengers (not this Dark Reign shit), The endings Sin City Yarns The Hard Good Bye and That Yellow Bastard, Ronin, The Killing Joke.
Vid Games: The Ending to MGS3 and MGS. All of the Half-Lifes ending's (excluding the episodes because they are sequel ridden). Thief: The Dark Project, Jak and Daxter Series (when I was little...).
Best ending ever tho has to be, when we die, because we finally are rid of all opinion and just move on in the earth, or go to Heaven/hell: what ever you subscribe to.