Just bought an SD card and installed ezPDF. It looks very nice. But by default it opens file system on the SD card not on your home directory where all pdf are downloaded by the browser. And it doesn't show the home directory.
Luckily someone posted instructions on B&N nook forum explaining how to mitigate that. I copy and paste them at the end. After following those instructions I am able to see "My download" directory and open all pdf file without problems. And ezpdf allows you to rotate, zoom, search and many other things that I am still exploring.
The only drawback is that it doesn't change the file assosiations, so one cannot open a pdf with ezpdf by simply clicking on it. But maybe someone has already posted a solution to that too.
Instructions: "To get to your main folders on the nook in ezpdf (not on the card) go to the import icon (the little rectangle with the arrow on it) It will show the directories available on the sd card. touch the main directory at the top mnt/sdcard/ and tap ok. You get a message that says unable to copy or move. Then go back into the import icon. This time you will see that you are at the root of the Nook Color itself, your file folders are under media the my files. Not very intuitive but it works."