Lax.js - Create beautiful & smooth animations when you scroll
Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
ScrollMagic - The jQuery plugin for magical scroll interactions.
BuildFire - BuildFire is the easiest way for small businesses to build a mobile app in a matter of minutes for iOS and Android.
WOW.js - Animate elements on-scroll to catch attention. Such Magic.
MIT App Inventor - App Inventor is a cloud-based tool, which means you can create apps for phones or tablets right in your web browser.