I just discovered this iPhone App called Chinese Flashcards that helps you practice reading Chinese Characters on the go.  I've been using it while on the subway, elevator, waiting room, and being the true nerd I am, while walking down the street.  I recommend it for beginners that want to get familiar with basic Chinese characters as well as advanced speakers who want to brush up on their vocab.  Reading and writing Chinese characters is a hard skill to keep up.  If you don't live in China or Taiwan it's easy to quickly forget the meaning of common characters and how to write them.  Even some of the Chinese-Americans I know, whose families speak only Chinese at home, can't read and write a lot of basic vocabulary words because they are out of practice.