Process
This website has links to resources to help with math differentiation and many other subject areas. Check it out.
You may find one or both of the following Power Points useful. They are taken from schools who differentiate math instruction.
Math stations is one strategy to use when implementing differentiated instruction. This presentation may be a good resource for you.powerpoint math stations.ppt
This presentation is a little more lengthy, however it does have some good information. It covers more general math differentiation strategies. It is a large file so I had to upload it in to three parts.
You have had the opportunity to review several resources over the past few days. I am sure you are saying enough already!! 
Ok it is time for mercy. 
I have listed some additional resources you may want to check out n
w or sometime.
A rather meaty article about problem solving.
This one has some specific data. You probably won't like it unless your a data Geek like me