I've had the question recently (after finally buying a Kindle - it was a *very* discounted refurbished one) about how to read a PDF file on an e-reader. If you've had the same question, I'll spare you the trouble of searching the interwebz to find an answer. (And if you read e-galleys from publishers, you're likely to get a PDF or similar file for a review book.)
Email the PDF file to your Kindle email address. Didn't know your Kindle had an address? Well, it does! :) It is the same amazon.com address associated with your account but instead of @yahoo.com, etc., it is @kindle.com.
Example: If my normal email is: firstname.lastname@example.org, my Kindle email is: email@example.com
If you want the PDF converted to make it easier to read, you must put "convert" in the subject line when you send the email to yourself. Easy peasy!
You can also plug in your Kindle to your computer via USB and transfer files to it. Open "Computer", "Kindle", "Documents". You can typically click and drag files into this folder. Check the home screen to be sure the file is there before you leave the computer.
You first need to download Adobe Digital Editions for free on your computer.
Plug in your Nook, authorize the ADE to view your Nook. This *should* then allow you to add the PDF to your Nook for reading.
However, it has been stated that reading PDF on the Nook is annoying. Sometimes the formatting is off. You can turn the PDF into an ePUB format. Wondershare is supposed to be a good conversion tool.
All that to say - the Nook isn't the best at PDF reading. (Sorry!)
You can also just read the PDF on your computer. I know this is difficult for a lot of people with a desktop computer. I like to read PDF on my laptop because I can go sit on the couch with it, you know, actually on my lap. ;) If you don't enjoy reading on the computer, be sure to get up and take breaks for your eyes and your body. Otherwise, you're going to put your angst of sitting for hours on the book you're reading. :)