Zimmer Twins (http://www.zimmertwins.com/)

Animation is made simple thanks to the Zimmer twins, Edgar and Eva, the animated young characters who star over and over again in the mini-movies on this site. Users can piece together clips of the twins interacting and speaking (through typed words in speech or thought bubbles) through whatever adventures their imaginations create. Choose a theme, create an ending to a “starter,” or simple create from scratch by piecing scenes together. Young animators can save their work for others to watch, rate, and comment on. This safe, satisfying romp into the world of animation lets kids exercise their creative muscles and hone their storytelling skills while offering enough limits to keep beginners from getting overwhelmed.

Online interaction: Users can interact with each other by posting comments about individual movie clips. Paid members can post unique comments, and those using the site for free can choose from an extensive set of prewritten comments. Comments by paid users can be flagged if inappropriate, but are generally positive, supportive, and constructive. Site administrators seem to be diligent in enforcing the site's code of conduct.