I've been using my Dell Axim x30 as an ebook reader, converting most files for mobipocket or my chm reader. PDF files and comics were just not readable on my PPC.
I just picked up an acer aspire one at Best Buy for $379 canadian.
http://en.wikipedia.org/wiki/Aspire_One
I got the xp model w/ 120 gb HD and 1 gb ram. It weighs about 2 lbs which is about as heavy as an average hard cover book, and half the weight of a normal textbook.
The resolution is fantastic! It has an 8.9 inch screen with 1024x600 pixels. I can use cDisplay and rotate the screen sideways and my comic books are fully readable. The netbook seems to vent heat from the left side where the adapter is so I just prop it up like a book on it's right end with the screen rotated and use the page down and arrow buttons to navigate.
I am careful not to turn the netbook on it's side until the files are done loading as to minimize shifting the hard drive while it is active.
PDF files don't work sideways quite as well since they aren't the same aspect ratio as the comics. I can read them but the text on some books is a bit tiny for my eyes. They are fantastic to read when the netbook is in a normal position. I'm hoping to find a pdf reader that is as comfortable as cDisplay is for page flipping.
The acer aspire one's battery life is about 2.5 hours with the 3 cell model. I hear a 6 cell battery exists that gives twice the battery life. For my purposes the 3 cell battery is enough. I read on a plane or on the bus occasionally, but I mostly use this at home for reading/surfing/watching in bed or on the couch where an outlet is readily available.
I may pick up an eink reader at some point for reading fiction on the beach for hours, but the acer aspire one suits my current needs. Overall I am highly impressed with this netbook.