I could not make nook color working for adb. I could not find the tools->application->development on my nook color. How could I enable the usb debugging mode.
On your Nook-Color screen, using the settings icon from your apps list,
press Settings > Applications > Development > here you'll see a list, the top button should be USB debugging press that.
Also while you're there press "Allow mock locations"; that's helpful for some sites that need GPS reference.
Under the Applications menu you'll see "Unknown sources"; you may want to press that and leave it checked if you have a rooted device and plan on apps from other sites than Market.