When I think about how I only got into Clarke in the last year, I feel remiss in my geekhood and I get the overwhelming urge to justify my nerd cred. But then I remind myself that I personally ran a one-sheet weekly newsletter about The X-Files for two solid years in high school and I feel better about myself. That's a whole other post, though.
If you're any kind of sci-fi fan you should be reading this man, because I've never read anything simultaneously very hard and very accessible in my life. It's not "soft" sci-fantasy/space operatic subject matter; Clarke writes speculative stories that force your brain to both expand and collapse in on itself until you're asking questions about humanity you never even considered before. How would the human race develop without religion of any kind? What kinds of people should we send to represent humanity to an alien culture? How the fuck long could we possibly survive as a society if our consciousness lives for thousands of years inside computer memory banks?
It very much represents how I try to write sic fi stories myself, so now I have a good (read: BEST) guide to that style. The few books I've read are already some of my favorites ever:
Rendezvous With Rama
Rama II
The City and The Stars
The Songs of Distant Earth
Go forth and read!