Banned from reading

Anita of Fighting Inertia is considering setting herself a challenge. To read all the books on the Time Magzine List of 100 Best English Language Novels from 1923 to the present.

In her post she asked what her readers thought of this, and put the entire list in there, and she highlighted all the ones she'd already read in the past. After scanning down the list I commented that it was interesting how many on the list were also in a box set of books that I had recently purchased: The Penguin Banned Books Collection.

Anita then asked for a list of the books in the collection or a link to a page about it. So here's the lowdown.

The box set I bought consists of 11 books that have at some time in the past been banned, although they are not now. The books are listed here with the country that they were banned in, and why they were banned.

A Clockwork Orange - Anthony Burgess (US: social obscenity)
The Master and Margarita - Mikhail Bulgakov (USSR: radical politics)
Go Tell it on the Mountain - James Baldwin (US: social obscenity)
Of Mice and Men - John Steinbeck (US: obscenity, politics, still being disputed as recently as 2003 in Illinois)
The Great Gatsby - F. Scott Fitzgerald (US: obscenity)
Animal Farm - George Orwell (USSR: anit-communist)
Things Fall Apart - Chinua Achebe (Kenya: Congo, obscenity)
Poet in New York - Federico Garcia Lorca (Spain: radical politics)
Heart of Darkness - Joseph Conrad (Poland, Germany & USSR: political censorship)
1984 - George Orwell (Cuba: radical politics)
Lolita - Vladimir Nabolov (France, Argentina & NZ: obscenity)
One Day in the Life of Ivan Denisovich (USSR: set in a labor camp)

This is obviously a very small selection of all the books that have ever been banned, Wikipedia has a good page listing many of them, but it's by no means complete.

I've already read three of the books from my collection, and while it's easy to see why two of them (1984 and Lolita) were banned, I'm at a loss to understand why the third, Of Mice and Men, was banned for the reasons given, and why it's still being protested even now.