You might want to ask if iDisplay (
https://market.android.com/details?i...alscreen&hl=en) works with rooted Nook Simple Touch reader. I've heard it works with Nook Color (
http://forum.xda-developers.com/arch.../t-919782.html), so it might work with Nook STR, but there are no guarantees. In general I think this will be easier to accomplish w/ Android.
Given the negative reviews of iDisplay, though, I am guessing the results will not be very good even if it is possible to run iDisplay on Nook STR.