Wikipedia
Skritter is a tool for learning Chinese and Japanese writing with stroke-level feedback, tone practice, audio playback, definition practice, and progress feedback. Skritter is owned by Ohio-based start-up Inkren.
Skritter began when one of the founders saw a Nintendo DS game using the stylus and thought a game-like approach to learning Chinese characters would be effective. The service started in beta in 2008 and was launched in April 2009. In August 2009 Skritter partnered with ChinesePod to add additional audio recordings and integrate the two sites.
Skritter was described in The New Yorker as "a pleasant distraction," and a blogger for CNET Asia said it "has the potential to boost any student's Chinese character reading and writing ability quickly and efficiently."
In June 2012 Skritter launched its iOS app which allows users to do their study on any iOS device. The app has been a huge hit and has doubled the usage of Skritter.