<x-gif> is a web component for flexible GIF playback. Speed them up, slow them down, play them in reverse, synch multiple beats to a rhythm, synch them to audio, whatever you like.
It fetches the GIF via Ajax, slices it up and thus let’s you do all of the above with a simple GIF image. Very cool!
Check out the demo.
It’s released under an MIT license so you can use it in almost anyway you choose.