It warms my heart to see all the references to Neal Stephenson - Cryptonomicon is on my top 5 books of all time list, easily.
I'm currently trying to work my way through "Mason and Dixon" (Thomas Pynchon). I read Gravity's Rainbow by him when I was in the Peace Corps and absolutely hated it (but I finished it, because I had no electricity and nothing but time on my hands after 7 pm). However, I was moved to give him a second look by subsequent recommendations from friends, and more convincingly, from other authors who I really love (such as Neal Stephenson and Tom Robbins, both of whom seem to be influenced by Pynchon's style).
Mason and Dixon is good. The writing is pretty extraordinary, I'd have to say, but like Gravity's Rainbow, it's hard to tell what the hell is going on a lot of the time. And Pynchon's contempt for such literary details as "plot" and "clarity" is monumental. Overall though, I'd definitely recommend it to someone who was really into literature - he's an important author.
If I had to give a random recommendation, it would be for Peter Carey, especially "The True Story of the Kelly Gang." He's a fantastic writer.
I appreciate that recommendation for "Blindsight"; it sounds intriguing.