Clarke was one of the the all time greats, and his books will be remembered for as long as people still read science fiction. These days he is best known to the general public for his role in 2001: A SPACE ODYSSEY and for his RAMA series... but to my mind his masterpiece is CHILDHOOD'S END, one of the best SF novels ever written, and a true mind-blower when it was first published. Many of his other early novels deserve to be rediscovered as well, especially AGAINST THE FALL OF NIGHT (later revised as THE CITY AND THE STARS, but I prefer the original version, partly because it has such a spectacularly great title) and THE DEEP. He wrote some stunning short stories as well, including "The Star" and "The Nine Billion Names of God." His TALES FROM THE WHITE HART stories were fun too, in a lighter vein. Clarke lived in Sri Lanka during most of my adult life, so I was never able to sit down and have a beer with him at a convention, alas... but I felt I knew him all the same, from his writing. I think that was true for a lot of us.
A fine writer and a good man. He'll be missed.