While I am definitely no expert on Math Monkey I know a few basics about their overall curriculum that may be useful to you. Math Monkey is a legally recognized franchise in all 50 states of the US and essentially is an alternative teaching method and viable supplemental education focusing on math skills.
 
Math Monkey primarily uses the "Vedic" system of math. This is rooted in Indian arithmetic and is a way of performing calculations mentally, without the use of paper or calculators with an emphasis on fun games and activities to engage children.
 
Here is the mathmonkey website FAQ and a video clip of a news report on the math monkey program:
http://www.youtube.com/watch?v=KoSpYflucfI
http://www.mathmonkey.com/faq.php
 
Hope this helps!
-Alex