Karen at Books on the Knob has noted that HarperCollins has put hundreds of their e-book titles on sale at $0.99 each. They also seem to be on sale at B&N, but of course there doesn't seem to be any mention of it, nor a page you can go to for a list of them.
One way is to go to Books on the Knob and follow the link to Amazon, find any titles you want, and come back to B&N to buy them. Another is to follow this link to all 99-cent HarperCollins titles (many of which aren't on sale, probably because they're short stories and novellas — the ones with no struck-out "List Price"): http://productsearch.barnesandnoble.com/search/results.aspx?PN=HarperCollins&FMT=EP&PRC=0.99&STORE=EBOOK&SZE=100&SRT=SA
Doug, thanks for posting this! I had just bought 13 books from Amazon to read using my Kindle app, but as soon as I saw your post, I went back to Amazon, where I was able to return them all for a refund. Now I have bought them all at B&N to read on my (much easier to read) NOOK.