Magic is a CSS3 framework with many animations. Is simple to use and many animations are cross-browser compatible.

Collie is a Javascript library that helps to create highly optimized animations and games using HTML 5. Collie runs on both PC and mobile using HTML 5 canvas and DOM.

Synfig Studio is a free and open-source 2D animation software, designed as powerful industrial-strength solution for creating film-quality animation using a vector and bitmap artwork. It eliminates the need to create animation frame-by frame, allowing you to produce 2D animation of a higher quality with fewer people and resources. Synfig Studio is available for Windows, Linux and MacOS X.

Tumult Hype’s keyframe-based animation system brings your content to life. Click “Record” and Tumult Hype watches your every move, automatically creating keyframes as needed. Or, if you’d prefer to be more hands-on, manually add, remove, and re-arrange keyframes to fine-tune your content.

animate.css is a bunch of cool, fun, and cross-browser animations for you to use in your projects. Great for emphasis, home pages, sliders, and general just-add-water-awesomeness.