I haven't tried the Skritter iPhone app for learning Chinese characters yet, because that isn't my language of focus right now. But I wanted to save that this video so I can find the app again. The basic idea behind their app is that you write the characters or kanji yourself to learn them. They have a version for Chinese and Japanese. They have an online version so you can test how their program works.
I found mention of Skritter at HSK东西, which is a site that has some great tools even if you're not interested in trying to pass the HSK exam because for different high frequency characters, they share other characters those show up within.