If you are using (and loving) your Android as much as I do, you have it close by all the time. So why not learn something while you're looking at it?
Our friends at px0.de have created a screensaver of the 100 most frequent (simplified) Chinese characters, their pinyin and the corresponding translation! This way you will be reminded of a character (or learn a new one!) whenever you look at your idle phone/tablet!
Note: If you own a Kindle, why not head over to http://px0.de/chinese-kindle-screensaver/ - there is a free screensaver with the same content that will work on all 2.x, 3.x, and 4.x Kindles!