I just cam across a new app for the Nook. While the Nook can use Android apps, this is the first one developed specifically for it. From the project summary:
Trook is an application for the Nook that can download books from Stanza catalogs or OPDS content. It can also read RSS or ATOM feeds, show associated web pages or download audio files from such feeds. In addition, it lets you browse your Nook's document folders (and preserves folders, and shows cover images -- hooray!) Finally, it can also install more applications, if they are linked from a feed.
You can find more information here.