I am sorry, in my enthousiasm I forgot that "works" is kinda vague. I did a lot of different things that night, so I don't know exactly what the winning combination was, but I think this is what made me get access to the market.
First I set the nook back to factory settings. I took NTGAppsAttack and deleted the MarketUpdater. I rooted the Nook and installed NTGAppsAttack. Next I side loaded Opera (file found in this topic) and a version of Market I found online that should work with Android 2.1. When I opened the Market and logged in, I saw the buttons for a very short time and hit "accept" as soon as I could. A server error showed up and I assumed it didn't work.
Next day I opened the Market to see whether I could find a way to fix the error and was surprised to see just the Market. It didn't (and still doesn't) show any apps, but I didn't get any errors. So I went to Play on my laptop and found my device was registered. Now I am able to push apps to my nook via my laptop. Since I need just a few apps for a project in which I am going to use the nook this method will work for me.
OK, so the scenario goes like this?
1. Root Nook.
2. Side-load Opera Mobile (order here is logical, but just so it's there before trying to access Market because stock browser is dead)
3. Remove MarketUpdater.apk from NTGAppsAttack before installation
[this makes sense because at this point it's not likely Google will respond with an update for an Android 2.1 device since the PlayStore has a lower OS limit of 2.3--I think]
4. Side-load your version of Market app (vending.apk)--Can you post this? Maybe it should just be added to NTGAppsAttack before installing, replacing the one already in the package?
5. Open Market app and accept terms
6. Wait for access--this is not new. It can take as much as 24 hr. according to OP for actual market access after signing in.
Does that seem about right?