I think I pay a lot more attention to revising the opening of my novel than I do to revising the ending. By the time I get to the ending, most of the loose ends are worked out. It's like I feel, along with the characters, that the tension is over (and the tension of making all those revisions, too) and it's time to chill a little.
I've written before about what I think is important in a story ending. But after reading what James Scott Bell has to say in Plot and Structure, I think my ending needs a little more attention. Some of his points that stuck with me are the need to sum up the characters feelings and the emphasis on carefully choosing words and descriptions.
Bell recommends generating at least 10 alternative endings, then waiting a day or two, and then choosing the top 4, deepening them and choosing the one with the best twist. Hmm. I've tried 2 different endings for my story, but I might try this, just to see if I come up with something that's even more exciting. I want to create an ending that will make the reader think, wow!