Hi,
I have found that I use the extender module in more and more projects and once you master it, you can start to branch out into unsupported peripherals or ones that suit your needs specifically. With the extender, you are essentially dropping directly into NETMF so any NETMF documentation is appropriate. One place that I can recommend as a start is the NETMF support on the GHI site. http://www.ghielectronic...t/dotnet-micro-framework. This page talks about a number of interfaces that you might run into when attaching something through the Extender interfaces. The two obviously missing interfaces are I2C and SPI. If you need to use those interfaces, look for NETMF examples which will be able to help you out.
Good luck
Colin