I'm a book addict too, and always have one or two on the back burner...that's why I _love_ ebooks and reading on my ipaq or clie (though the ipaq sees most use these days).
There are some books that just live on the storage card, no matter how long it takes to re-read them - anything by Tolkien, the Harry Potter series, etc
I still love isilo as a reader, but use eReader (formerly palm reader) if I must, or uBook for PPC (which is my favourite - reads text, doc/pdb, rtf and html files compressed in zip format, is very configurable, and is free!