I expanded on Indirect's bootable root sdcard and create an image that includes a update.zip image. The purpose of this is to root your Nook Tablet so additional software can be installed from the Android market or other sources. You will need a Micro SDCard that is at least 2 GB. If you want to add additional applications, flash this image to the sdcard then put your sdcard in the computer, open up the update.zip file and add your applications to the data folder. This has been tested on 1.4.0, 1.4.1, and 1.4.2 and everything works. Once your nook tablet has been root, you can reformat your sdcard from within the nook and use it as you normally would. Remember, if you have to do this again, you can just reflash the image to the sdcard.
This will add the following:
unknown sources hack
ez file explorer
Home Manager (allows you to switch between launchers easily)
NT Hidden Setting
Amazon App Store
Slashtop HD (Free from getjar)
Flash the image to an SDCard greater than 2GB
Power Down Nook
Put in sdcard
Choose "Apply update.zip from sdcard"
When it is finish, remove sdcard and choose reboot.
Thanks quid246 for pointing out an issue with the permissions.
Download image file:
Download imaging software