I used TouchNooter found at XDA-Developers [N2E][1.1] TouchNooter 2.1.31 - xda-developers
. You will need an SD card, a card read and writer and WIFI. Follow the directions carefully and be patient. After doing everything right, you may not be able to log onto the Market for a day or two.
You need to download WinImage from Download WinImage
which you use to create a TouchNooter SD card. The directions for this step are not very specific.
1. Unzip the touchnooter-2-1-31.zip file on your desktop
2. Plug in your external SD card to your computer (best to use an empty card)
3. Start and use WinImage Disk-Restore Virtual Hard Disk Image
4. Select your SD card, then select your TouchNooter file
Follow the rest of the directions. After logging onto YouTube and logging off, it may take awhile before you can sync Gmail. Be patient. It took me over a day before Market worked. I ended up uninstalling the YouTube app the next day, tried Market several times and it started working fine. When you are done, you can format the SD card and re-use in your NST.
I installed a couple of games, Kindle, a financial calculator, a screen off widget and set up my Yahoo email. I also made the ADW launcher the default for the home button and programmed the lower left and right buttons with Nook Touch Tools for Back and Menu.
Another resource for rooting the Nook Simple Touch http://nookdevs.com/Nook_Simple_Touch/Rooting