Animation

Pencil (Download: Mac - Linux - PC)
http://www.pencil-animation.org/
Create traditional hand-drawn animation. Free open source software, complete with a user's manual.

Pivot stick animator (PC only)
http://psfao.com/
This free software download is a great asset in my classroom. The kids create beautiful animations and this is a very useful link.

Flashberry.com (PC only - some aspects free)
www.flashberry.com/
Free flash openers or introductions - but must use IE browser to create

Scratch (Download: Mac and PC)
scratch.mit.edu/
Create your own interactive stories, animations, games, music, art....

Hype ( Download: Mac only - fee)
http://tumultco.com/hype/
Create Flash-like animations. Save as html5 web page. Viewable on iPad without special plugins.