Black Rock Ledger
From Diablo Wiki
The Black Rock Ledger is made up of pages strewn around Sanctuary. There are six pages known to be in the game although the original ledger is at least 42 pages in length.
It is not known what the pages are for or if more will be added with patches but it's hoped it'll lead to another secret level like Whimsyshire.
 Clues and Theories
If the numbers seem familiar it might be that you recognise them from the TV show LOST. The numbers were a running story element throughout the long-standing series and caused much speculation. The first letter from each of the six pages spells out DHARMA a secretive initiative that appeared in LOST. If the acronym is significant in Diablo 3 that would suggest there are no more pages in between those already in the game.
Staying with LOST, The Black Rock was a mid-19th century ship that became shipwrecked en route to a mining colony and ended up on the other side of the island, well away from the sea.
Page 4 ()
Damn, I always thought that being a first mate would be more exciting. I guess I shouldn't expect much from a mining expedition. Ever since we set off from Kingsport, all I've done is sit out on deck and watch the deckhands argue.
Page 8 ( )
Haven't been able to get much sleep these past few days. Apparently my sea legs aren't as sturdy as I thought they'd be. I've vomited more times than I can count, and every time Captain Hanso offers me some ale, I have to come up with some excuse to decline.
- Captain Hanso - Reference to Magnus Hanso who captained The Black Rock ship that appeared in LOST
Page 15 ( )
After three straight days of this storm, I'm almost convinced that this ship has some sort of curse on it. Each week brings some new trouble that I have to deal with. I'm not sure what will give out first, the ship... or me.
Page 16 ( )
Reyes tells me that it was some colossal wave that did the ship in. I was down below when it all happened. Several of us survived the wreck. The rest of them have gone off to try and figure out where the hell we are, as if any of that matters.
- Reyes - Reference to Hugo "Hurley" Reyes, one of the main characters from LOST.
Madness, complete bloody madness. The captain has disappeared into the desert somewhere, and the rest of the survivors are convinced there's some sort of monster after us. I'm starting to think the crewmen that died in the wreck got the easy way out, lucky bastards.
- There was a mysterious black cloud that appeared to be sentient and would snatch people away in LOST. There is a black tornado that sweeps across the Stinging Winds. It seems to appear more often in the east of the east portion of the Stinging Winds.
Page 42 ( )
All the rest of them are dead now... I'm the only one left. Strange deformed creatures attacked the wreck, where most of us were sleeping. I managed to get away safely... but I don't imagine it will be that way for long. I can hear... giggling in the shadows, like this is some kind of game. -- First Mate McMahon
 Locating the Black Rock LedgerStinging Winds. A miner will appear next to the wreck of a ship which can spawn in one of the four locations. These are marked on the map below.
As you approach him he will say Be careful... this ship is cursed by demons! We should be safe as long as we don't disturb it! Unfortunately at that point a Fallen Lunatic runs up to the miner and explodes taking the miner with him in a bloody mess. The miner will always drop one of the six pages.
The pages can not be sold but they can be traded in-game so if you get duplicates you can share them with friends.
To farm this area choose the quest City of Blood at the menu screen. You'll appear in the Hidden Camp. Take the Waypoint to Khasim Outpost. Just outside of the south eastern exit of the Outpost into the Stinging Winds (east) you will pass a Checkpoint so once you've searched the four locations you can Leave Game and simply Resume at the menu to begin at that checkpoint and visit the four possible sites again.
The shipwreck may not spawn at all sometimes.
 Comments From Blizzard
Blizzard remain closed-lipped about what the pages do. There has only been one direct mention of them and it offers no insight into what the pages do.