Maxgif almost couldn't be simpler: just feed it a gif and it'll frame it, stretch it across your browser window and give you a link for sharing.
Technically all it's really doing is scaling the animation. But simply changing a gif's size can actually be transformative. Really! Like it is with this one or this one or this one or this one. Or this one (via). These gifs are suddenly become cinematic, almost.
Try it with a few of these by right-clicking the gifs, selecting "copy image url" and pasting it into Maxgif (or just click the Maxgif links beneath each one):
See? Post yours in the comments.