I have a Nook and I love it. I was able to compare the Sony ereader, the Kindle and the Nook and I like that there is no monthly fee (sony) and the Nook feels like a better quality product than the Kindle.
You can get the Nook with 3G (download anywhere there's a hotspot $199and 69.99 protection plan ) or just WiFi for a lower price ($149, $44.95 protection plan) and I do recommend you get the protection plan. It extends the manufacturers warranty to two years and covers all accidental damage. Even if you drop it in the pool.
You can side load PDF's so just get your porn in PDF format and you're good to go. I got mine so I can take my tech manuals to work without having 200 books there. Plus there's a search feature so I can look for specific terms (myofascial, ankylosis, throbbing), very handy.
What I'm waiting for is put out by Plastic Logic and it's called Que Pro Reader.
http://www.plasticlogic.com/ereader/ It's more for business people and it will be sold at Barnes and Noble. It's sexy, it has a full suite of Microsoft office programs and is a full ten and a half inches of touch screen that allows annotation. It will come with 3G or WiFi, like the Nook. My heart actually beats faster just looking at it.
Yep, Star Trek is getting closer every day.