Full OS boot from SD (working)
This is one of those things that I've always assumed would work, but I don't think I've seen anyone actually confirm it or talk about it yet. Before doing any of this I did a clean wipe of everything, just to avoid confusion on my part.
Step 1) I DD'ed the entire filesystem to an 8GB microSD that I have.
Step 2) Mounted p1 from SD (which is a copy of P1 from internal)
Step 3a) Pulled ramdisk
Step 3b) Extracted ramdisk
Step 3c) Changed all mmcblk0 refs to mmcblk1 in init.rc
Step 3d) Recompiled ramdisk
Step 3e) Pushed ramdisk back to p1 on SD
Step 4) Shut down Nook, reboot, confirm via mount command that all mounted volumes are mmcblk1
As I said, this is nothing revolutionary, but I figured it could be good for testing, especially if anyone wants to take a shot at a potentially dangerous mod like recovery or installing a fresh /system. Also, if I ever seriously messed up my internal memory, I would hope to be able to somehow recover by booting via the SD and being able to DD to the internal memory that way.