The Puppet Masters

Peter Watts's Blindsight - easily the best SF novel I've read in the last decade. I haven't got round to Echopraxia yet, but I doubt it'll fail to live up to its predecessor. Also, while I have no use whatsoever for Stross's "Singularity" stuff, his Laundry Files series excels, especially for an inveterate old Lovecraft fan such as myself. If you want a taste, there are some shorts available online -- "Overtime" and "Funny Farm" are good places to start; "Equoid" is the most recent, but it's not representative, and it's also the weakest entry in the series as a whole due to its poor characterization and reliance on shock and gruesomeness rather than the more insidious sort of horror in which the rest of the series specializes.…

If you like Foundation, you might like the Ringworld series by Larry Niven. Ringworld is a classic. Robert Heinlein's books are great. Some come to mine are The Moon Is a Harsh Mistress, Starship Troopers (much better than the movies), Stranger in a Strange Land, Double Stars, and The Puppet Masters. Ursula K. Le Guin's The Left Hand of Darkness is amazing. The Earthsea series are fun read if you want to get beyond SciFi.