I find I'm using my Nook app more and more. I have versions on various PCs, netbook, but I'm using it mostly on my 7" Galaxy Tablet. (Won it in a drawng.) In fact I use it mostly as a reader.

At this point I probably have 25 books dowloaded. Is there no way to organize them beyond the archive feature? It's frustrating to simply have a long list of books and not be able to categorize or group them.

You should be able to put the books on shelves.  I have a different shelf for each author.  To do this go to your library and click on Add Shelf, type the name of the shelf, and then save.  Next to the shelf name you should see an edit button.  Click on that and it will bring up all your books.  Just click on the books you want in that shelf and then hit save.

Here is the Nook user guide.  Search for shelf and you will be able to see more detailed instructions if you need them.

Sorry - I don't think I was clear. I don't have a Nook, but the Nook App which you download onto a PC, tablet, or other device. Since the app is free, I understand it's not going to have all the bells and whistles of the full-blown Nook.At least on my version, I cannot finda any option to create shelves.

I don't think there is.  I have a Nook, and I have the application on my laptop and Droid, but I don't see any way to organize, either. 

Sorry Jo, I guess I misunderstood you.  I also don't think there is a way to organize your books.  You could look at the Barnes & Noble forums to see if they have any ideas.