It's funny that most people other than the OP (and theadvancedapes) have posted only fiction. As will I, in no particular order.

1. Infinite Jest by David Foster Wallace. A behemoth of a book, but well worth it. One of the most memorable books I have ever read. Unfortunately I gave it to an ex-girlfriend, and don't know if I'll get it back.

2. The Count of Monte Cristo by Alexandre Dumas. Another large book. I was at times put off by how, well, amazing the main character basically is, but the book is fantastically gripping, and I love the sense of age I get off of it.

3. The Wind-Up Bird Chronicle by Haruki Murakami. The first Murakami book I read, and the one that made me fall in love with his writing. He has a way of combining the everyday and the uncanny that I can't get enough of. Well, actually I can; 1Q84, his latest offering, was a disappointment.

4. 1984 by George Orwell. Along with Murakami, he's one of my favourite authors, and I've read many of his books. 1984 was also the first of his that I read (unless it was Animal Farm) and I thought it was brilliant. Besides, 1984 is almost obligatory in Top Books posts... Speaking of non-fiction, Down and Out in Paris and London is a great read, too.

5. A Hero of Our Time by Mikhail Lermontov. It's difficult to put my finger on why I like this book so much.

I also like A Song of Ice and Fire, but it's not one of my favourites. When's the next book coming out?