Time to get this thread back going again.
I notice many of the suggestions in this thread so far focus on the war in Europe. I spent the last year reading various WWII memoirs, mostly pertaining to the Pacific theater of operations. I must admit part of my interested was due to my anticipation of the (then upcoming) miniseries on HBO, "The Pacific"
So, to start off my recommendations, the following three titles were used as the basis for
The Pacific miniseries, and are
very compelling reads:
With the Old Breed: At Peleliu and Okinawa - By Eugene B. Sledge
China Marine: An infantryman's Life after World War II - By Eugene Sledge (published posthumously from discarded material from his
Old Breed manuscript)
Helmet for My Pillow - By Robert Leckie
I'd recommend people read them if they plan on watching the miniseries down the road at some point. They did a fair job in the miniseries, but of course nothing compares to the books. While I admit my initial interest was somewhat shallow, since I was just "preparing for a movie" basically, I ended up developing quite a substantial interest in the PTO as a result.
Additionally some really great titles that I don't see mentioned here include:
Ghost Soldiers - by Hampton Sides
Flags of our Fathers - by James Bradley
Flyboys - By James Bradley
(his personal bias got under my skin in this one, but it was still a very informative read)
Goodbye, Darkness - By William Manchester
In Harm's Way: The Sinking of the U.S.S. Indianapolis and the Extraordinary Story of Its Survivors - By Doug Stanton (already mentioned previously, but I wanted to give it my hearty endorsement, as if that means anything

)
Brotherhood of Heroes: The Marines at Peleliu, 1944--The Bloodiest Battle of the Pacific War - By Bill Sloan
There are so many more I've yet to read, and, quite frankly, I'm still interested in the Pacific theater, so I'm always open to new suggestions for that. I much prefer the infantryman's view as opposed to books devoted to the tactics and high-minded strategy of great Generals.
Lastly, I'll add that one book I personally
don't recommend is Hugh Ambrose's
The Pacific which was rushed to market as a companion piece to the miniseries, and while I read it, it was pretty terrible. I'd much rather people read the memoirs of the men themselves, as well as Brotherhood of Heroes as movie tie-ins, than that piece of crap the younger Ambrose put out.
Hopefully this can get the thread going again, I'd love to hear what any other WWII buffs have to suggest.