Try some Stanislaw Lem for something different. His Master's Voice is about trying to decode an alien radio transmission, and I remember the characters resembling actual mathematicians pretty convincingly. Solaris is also good, and a nice counterpoint to the overly straightforward can-do attitude English-language SF from the same era. The Cyberiad and The Futurological Congress are absurdist humor. From stuff I haven't read, Tales of Pirx the Pilot gets mentioned a lot, and Golem XIV is about a self-improving military AI.
Lem strongly seconded. I just listed him in my own comment because no one had mentioned him yet, and alas, three minutes later you bring him up.
I have never read very much Science Fiction, unlike some of the people here on Less Wrong, and I think I would like to. At least, the few books I have read I enjoyed. I've read a couple of books from Asimov's Foundation Series, two Michael Crichton books, Twenty Thousand Leagues Under the Sea by Jules Verne, and an anthology of SciFi short stories (no really famous authors) that my dad owned.
That list looks very short. I just finished reading a fiction book, and am looking to start another. Recommendations? What are the two or three books I simply must read?