Now I know exactly what you're thinking - the man has no shame. You're right!
I'd like to unabashedly and blatantly plug http://www.pocketchinese.com , a free, open source program for learning Chinese on your mobile phone. Which, er, I wrote.
Here are some of the cool features (OK I'm biased, I wrote it):
*All the quizzes are stored on a wiki (like Wikipedia) where you can create your own quizzes. These are then available for download to your phone.
*If you have a pen phone, you can test your knowledge of how to write the characters.
*If your phone can display Chinese characters, you can test your reading vocabulary.
*Regardless of what type of phone you have, you can test your englishpinyin knowledge.
*Seamlessly integrates the stroke order animations from lost-theory.org
*Quizzes and animations are available offline once you've downloaded them from the wiki, so you're not constantly caning your airtime.
Totally free and open-source and will always be.
Features slated for the next version (manana, manana, I know...):
*On-phone quiz creation
*Integrate support for Wikipedia's stroke order animations (much nicer than lost-theory's)
*Other cool, unspecified stuff.
Did I mention the program is available from www.pocketchinese.com ? Oh yes, I did.