In reply to fil:
Kindles can't read epubs: the main file format for electronic books. So they're kind of like a web browser that can't read html.
There are tons of free epubs out there plus there's free software to convert or even make you're own - so shopping lists, phone number lists, addresses etc can then be added to your book reader.
I got a Kobo Glo from WH Smiths. Very similar to Kindle but reads epubs. It also has a back light which is great for improved contrast in places with poor light.
The best ebook readers I think are Onyx - the OS is more open so you can add your own apps and they can even do stuff like play music.
If you need to use it for PDF's get a large (9") screen.