I don't recommend the Kindle yet. It's perfect in every way except for the large buttons on the sides - it makes it really difficult to hold without accidentally pushing the buttons.
The Sony E-Reader is the next best thing, but doesn't have nearly the library that Amazon has. They had a deal running on it for $50, I don't know if it's still valid:
http://www.fatwallet.com/forum...hreadid=745156&start=0
I've heard it doesn't import PDF files very well though. Also there are some more expensive readers that you can do things like draw on, but then you'll be spending $600+.