Oh I thought you meant as in the conclusion of a season or series lol.
Anyways, I love the second ending for the Madoka Magica series. This one is in very sharp contrast the the ending for the first several episodes (for a good reason), and it makes it work out really well, especially the first time.
http://www.youtube.com/watch?v=ZwqpYZ_LEqA
Was looking for one with English subtitles, and ended up finding a good English cover, so here's this instead:
http://www.youtube.com/watch?v=KQaymIKOJXI