There are quite a few I haven't been able to finish, but the one that stands out is Lord of the Rings. I've tried so many times and the writing style just bores me to tears.

Oh my god, I have like a million. I can't remember many right now but Obsessing Orlando is the most annoying thing ever. Jinx by Meg Cabot I couldn't finish. There's more but these are the only ones I remember

The Hobbit.

I had to read it for a book project in grade 6 and I couldn't finish it. I tried to read it again in jr high and then in high school but I still couldn't.

The story permise itself is good but it's the type of book I put down and forget about, and when I finally pick it up again (usually a few months later) I can't remember what's going on.

The only book I remember not finishing is the second book in the Diadem series. I've tried, but I always seem to forget to read it. I also never finished Harry Potter: Order of the Phoenix. Where did I put that...

The Anne Rice Vampire Series.. I struggled through Interview with the Vampire and I just could not get through book #2 of that series because I was soooo bored. >w<

Nanjing 1937 A Love Story

I forget the author...but yeh, attempted to read it recently and I think I got bored. But I'm guessing part of this was because the book was originally written in Chinese and was translated into English. So I'm guessing the translator didn't do the original justice. Apparently it got a lot of praise in China.

All the Harry Potter Books
Son of a Witch (sequel to Wicked) by Gregory Maguire

I loved Wicked because I was brought in to the character of Elphaba (and I loved the musical) the sequel didn't have the same effect on me so I just didn't really bother finishing it.

I never seem to finish any books that sound boring after about three pages, manga included. : ) When I try to read Harry Potter books, someone always distracts me from finishing. :l There's one series that I couldn't understand, but I forgot the name. : P Something about aliens taking over the world taking meaningless steps to stall for time for no reason whatsoever. :l

I couldn't finish Gulliver's Travels a few years back.
I started The Picture of Dorian Grey, but then I couldn't finish it because I got busy. When I came back to it, I couldn't get into it without starting over, so I didn't bother.

The first book in that series with cat warriors o_o (I forgot what it was called XP)
all the Harry Potter books except for the last one :P
and much more but I can't recall any of them >.<

There is only one book i haven't been able to finish. It's the Sing Languge book my bought me. it's the only book i wasn't able to finish. D:

The Grapes of Wrath. Everything else I've read I've finished.

I tried to read Ulyssis by James Joyce once, it was on a list of the greatest books of all time or something, but I got so lost. I don't even remember when I got lost but after a couple pages I had to put it down, it was making me dizzy! as for the 4th Harry Potter book, I've read that one many times, maybe it's because of teh length, I admit it does take a while to get through the whole thing though

The only book I can think of that I've never been able to finish is Go Ask Alice. I bought it in middle school at one of those book fairs. I've picked it up quite a few times over the years, determined to read the whole thing. I never make it very far, though. It just doesn't really grab and hold my attention.

Edit:
Oh! I forgot To Kill a Mockingbird. Same deal. I've picked it up so many times wanting to get through the whole thing since it's supposed to be so good, but I've never made it very far in it.

Me and books don't mesh that well. I tried and tried but gah. Classics are the worst. If I did finish some titles (only for reading assignments), I don't remember which were those. Even comic books and manga. Does school books count? I like those especially science, math and history (suddenly enlightened on one's geekiness).

There are only three books, that I've attempted to read and did not finish. Interview With The Vampire, Harry Potter and The Sourceres Stone, and Desperation.
Interview With The Vampire:
I was a few chapter's into it, and I took it to school. I had lost the book for about a month, before locating it in the library. I knew it was mine by the torn cover, and etched writing on the inside.
Harry Potter and The Scouceres Stone:
I began to read it, at about chapter two, I fell asleep. I tried again, but the first few chapter's are to boring and I kept falling asleep.
Desperation:
I had been reading it, almost at the halfway point. I went to my cousin's and she hid the book for the entire week I was there. She totally can't stand that I read at a college level, I know it...

There's only been one book that I've never been able to finish... and it was a book we had to read for school. >__>

Anywho, it was Heart of Darkness by Joseph Conrad. Sure, it's a really short little novella but OH MY GOD it was so dull. I just died. I REFUSED to finish it. God. I wouldn't have gotten through the first page if I wasn't forced to read it and do questions on it in class... but I didn't end up finishing it cause the teacher did such an awesome review of the plot that I never needed to actually read the book =3

The Aeneid. Not that I didn't want to. But I put it aside for more than a year then lost it when I moved. I feel bad about that because now I actually want to finish it. It was the verse version and I stopped reading right when Camilla appeared.

The Subtle Knife. It's the book after The Golden Compass. Again I want to finish it. And I probably will after classes start because then I can read it on the train like I normally read.

The Hobbit. Started it. Got about 50-70 pages in and totally lost interest. I don't intend to pick it back up.

"It" - Stephen King
It drug on FOREVER. I kept getting the characters confused. And I just wasn't reading very actively at the time, so it's very hard to follow if you only pick it up once a week. I'll try it again sometime, though.

"The Hobbit" - J.R.R. Tolkien
This one was a while ago. I don't honestly remember why I didn't finish it. I remember that I was VERY close to the end, too. It just started to bore me and I lost interest.

"Slash" - Slash
It was just so... uninteresting. Even as a GnR fan.
The first half of it was pretty interesting. After that, it just got so... ugh. There comes a time when tales of a junkie getting high just stop being interesting, you know? You can only take so many before it's like "DO SOMETHING ELSE, ALREADY."

Eragon
god,was that book awful.I tried to read it so hard,but then it just got so redundant and annoying...It took like fifteen pages to describe a snowy village.I just did it with two words: SNOWY VILLAGE!!!
And then when it came to describing that egg/rock thing.That was like five chapters and five hours of life i wasted there!!After that,I threw that trash across the room and picked up something else.

TWILIGHT
I hated that book from the first page, and managed about 3 pages before quitting.

Honestly, I dont see why its so popular. D<

The beginning of it sucks ass.
The rest is lame, but sort of cool at the same time.

We were assigned The Grapes of Wrath for 12th grade AP English and I just couldn't get through it.

Needful Things- Stephen King
I usually like his books, but I just couldn't pay attention to this one. I'll probably go back and finish it one day, but I just couldn't waste time forcing myself to read something when there are so many other good books out there.

The Book of Three- Lloyd Alexander
I know this is supposed to be a really great book, but I picked it up when I was way too young and ended up stopping in the middle because I couldn't understand it.

The Silmarillion - JRR Tolkien
I am a Tolkien fan, but I keep getting distracted whenever I'm reading this one. I prefer homey Tolkien to ballad Tolkien. I've read the beginning of this about five times, and gotten a little further each time. One day I'll finish it.

I very rarely start a book and then never finish it. I'm compulsive like that. These three bother me because I want to know the rest of the story.

I usually don't have a problem with finishing books, but there are a few that I just can't seem to read as hard as I try.

I don't remember the title but it's the book that comes after Interview With A Vampire- Ann Rice. I tried so hard to read that cause I was going to read the series but I stuggled to get through Interview With A Vampire and then read partly through the second book and just gave up.

Needful Things-Steven King
I thought It sounded interesting on the blurb on the back but I just got really bored cause it was so slow moving and confussing I later waych the movie and finally got what had happened in the book but I was so lost when I was trying to read it.

I'm quite sure there's others that I'm just not remembering the titles off but I try to only pick up books that I'm quite sure I will like such as books in the subjects that I like and I try to stay in the YA dept. of the libary and such because adult books can get really dry and boring and they drag out there stories too much.