I read PDFs on my n800 fairly often using Evince. For frequent consultation, I would suggest something with a bigger screen, as text will be quite small in rotated, full screen mode on the n800. I know a number of people like the irex iliad for hauling around large amounts of PDF documentation. It uses the same eink screen technology as found on the Sony Reader, but has a bigger screen and features a touchscreen, so you can make annotations to your documents. Highly recommended, but highly pricey as well.