My high school students of Japanese are using Skritter, and many of them are really using it to their advantage.
As a teacher, I would love to see a feature to be able to pick out words/kanji from specific sets of vocab and make a printable test to use the classroom; or, even better, a way to embed a link to take the test online and receive the results.
I currently use www.quizlet.com to re-type the words/kanji that I want to test. If a "create a test" feature was included in Skritter, it would be perfect!