All-time favourites are, in order of preference:
-The Monkey Wrench Gang, Edward Abbey
-Touching the Void, Joe Simpson
-The Road, Cormac McCarthy
-Into Thin Air, Jon Krakauer
-Perfect Storm, Sebastian Junger
-Power of One, Bryce Courtney
-Angels & Demons, and Da Vinci Code, Dan Brown
I have been on a bit of a history and classics kick recently. Just finished Gallipoli: The Fatal Shore, Catch-22 and Fightclub, and have 1984 and To Kill A Mockingbird up next. Also bought Born to Run on the advice of TFF, but that's sitting third on the book shelf with another Gallipoli book.
+1 for Grapes of Wrath.