http://www.pencil-animation.org/index.php?id=Home

Pencil is intended to be a simple programme enabling anyone to make 2D animation.

It is an animation/drawing software package for Mac OS X, Windows, and Linux.

It lets you create traditional hand-drawn animation (cartoon) using both bitmap and vector graphics. 

To find out more, visit  http://www.pencil-animation.org/index.php?id=Home

To download click here,  http://www.pencil-animation.org/index.php?id=Download 

Screenshots