iOS: The iPhone has a pretty fast camera, but to capture the exact right moment, you might want to take photos faster than your finger can tap. SnappyCam is a great solution to help you get the perfect shot.
The app is basically like burst mode for your phone. You just hold down on the shutter button, and it will keep shooting. Once you're done, you can select the best images from a touch-friendly reel, and export them to your Camera Roll, Instagram or email. Depending on your settings, you can get a whopping 20-30 images per second out of the app, at least for a few seconds until its buffer fills up.
As you might have guessed, this speed can come at the expense of resolution. At the fastest setting, you're basically getting cropped 1080p video frames. They look okay, but they won't be as good as lining up a shot with your iPhone's regular still camera.
If you dial the settings back to a still-impressive 10 shots per second, SnappyCam will spit out full resolution images (at least on my iPhone 5). Compare this to Camera+'s burst mode, which outputs diminutive 640 by 480 stills.
Unlike most camera apps these days, SnappyCam isn't going to shove a bunch of filters and editing tools down your throat. It's there to take a series of images very quickly, and it does this as well as any app I've seen.