I like the deadtree format too, but there are exceptions. The MSDN I always read online, and would think that a dead form is nearly useless, considering how I normally use it. Likewise, the perldocs I read online, and even though the same material is in the Camel book and other books that include module docs, I never use it that way.

For leisure reading, rather than looking things up, I found that my Casio PDA is almost "there". It's roughly the size of a paperback book, and has a 320x240 full-color display.