How can I persist data onto the Netduino?
SkippyFire, you can add an SD card using the v4.1.1 firmware and an expansion shield.  The Adafruit MicroSD expansion card also works.

There is a feature within .NET Micro Framework called "ExtendedWeakReferences" which can be used if you recompile the firmware and enable it--but I'd highly recommend using MicroSD instead.  Simpler, standard, and powerful.

Chris