The main reason I chose the B&N nook over the Kindle when I bought an ebook reader was the fact that the nook supports PDF discount viagra levitra and Epub. While the nook's PDF support is really only suited for text, it doesn't do a very good job with graphs and images, I find that I can convert most anything a nook-friendly format using Calibre.
One thing the nook handles surprisingly well is manga, Japanese comic books. The nook doesn't do so well with full sized American comics due to resizing (thus rendering text illegible), but the smaller form factor of manga is perfect for the nook's screen size:
A lot of manga is only commercially available in Japanese, and the English translation are largely done by fans. The translated files are available in .CBR or .CBZ format, which is really just a renamed zip file full of images. Calibre does a great job of converting the CBR files in to an Epub suitable for the nook. The pages are very readable, and the artwork looks good.
There was also some new nook firmware released today. While most of the attention is going to the new browser (in beta) and games, the page turns are noticibly faster in 1.3. They're now fast enough that I don't really notice them, and consider it on par with the amount of time it takes to physically turn a page:
The nook got off to a shaky start, but it's turning out to be a really nice ebook reader. The games are cute, but not something I see myself using much. Hopefully when the browser is out of beta it will allow for downloading books through it (right now you have to cable sync or use B&Ns app). Or better yet, I hope they let folks develop their own apps for them. A Calibre client for the nook would be great.