Hard to pick ONE most boring book I've read...I guess the Bible is up there though. Assorted other books where I thought, will this ever end??! Silmarrilion, definitely...although I liked The Hobbit and The Lord of the Rings. The Dune books. Any book by Isaac Asimov..I read two or three, and vowed never to pick up another of his books..I don't remember the titles I actually read though. But they read like technical manuals..I want to be entertained! If I want a technical manual I'll get one of those not a "fiction" book...
I plan on working my way through the "1000 books" list I found here, though, so I'm sure this will change
I LOOOOVE Hitchhiker's Guide to the Galaxy...I've read the book about 10 times over the years, and my ex-boyfriend from England had the BBC radio show on disc that I loved listening to. We've broken up though so I'm not likely to get my own copy

But dang I wish I could get that...hehe
~Yira