As others have said, the Nook Color doesn't have native support for cbr/cbz (and probably won't get it given the number of standalone "graphic novels" in the B&N app store), but it's ridiculously easy to install a full Android Gingerbread ROM on SD and use any app you like without even endangering warranty. At that point you have a capable Android tablet with a gorgeous screen and travel-friendly form factor. I haven't been using it much for CBR/CBZ as I'm at home a lot and my PC is great for those, but it's killer for web comics over at
http://www.webcomicsnation.com/
The display is so sharp, when I encounter an article longer than a page on my home PC, I often pick up the NC and find the article on there for a more comfortable read.