This link is a description and comparison of the different model of co-teaching.  The chart is very useful to determine circumstances that would be ideal for differing co-teaching models.

This link will take you to Differentiation Central.  The site is maintained by Dr. Carol Ann Tomlinson of the University of Virginia Curry School of Education.  The site is a wealth of knowledge on Differentiated Instruction.

This link leads to the Texas English Language Leaners Portal.  The site contains a lot of useful information and downloads in regards to assessment, professional development, accountability, etc.