You might consider Ivan Denisovich, CRussel, as it's readable, it's short and it won Solzhenitsyn the Nobel prize.
If anyone likes reading previews, if you didn't already know Goodreads offers quick previews on most books and so for the books nominated all you have to do is click the Goodreads link in the first post then click the preview button and voila. (and thanks to Tom for graciously ensuring that each nomination has a Goodreads link)
Also since I was looking at all the pages anyway, here are the Goodreads rating for each nominee in descending order along with number of voters:
4.40 - Harry Potter and the Philosopher's Stone (3,369,499 ratings)
4.20 - The Perks of Being a Wallflower (721,184 ratings)
3.99 - The Castle (22,853 ratings)
3.93 - One Day in the Life of Ivan Denisovich (58,215 ratings)
3.90 - The Northern Lights (788,056 ratings)
3.78 - Can Such Things Be? (306 ratings)
3.76 - The Earth, My Butt and Other Big Round Things (19,370 ratings)
3.75 - Candide (134,081 ratings)
3.73 - Beloved (200,763 ratings)
3.03 - Mein Kampf (15,942 ratings)