Most Significant SF Books

Tikistitch, PZ Myers and John Wilkins are going through a list of “Most Significant SF & Fantasy Books of the Last 50 Years”.
Considering I am a big SF reader, I was surprised as to how few of those I have read (only around 15!). Most of the titles on the list are just around 40-50 years old. I guess my preferences tend to be for either much older stuff or the most recent stuff (and no Fantasy, please).
I also tend to latch onto an author and read a lot by the same person. So, growing up I had my Heinlein phase, Bradbury phase, LeGuin phase, etc. More recently, I had a Greg Bear phase, a John Kessel phase, a Vernon Vinge phase, a Connie Willis phase, etc.
Anyway, instead of going through the excercise of bolding or not the titles on the list, I’ll point you to my own old list here for a taste of the stuff I like.
Update: Orac, Joseph, Moomin’ Light, Afarensis and Rob join in the fun. So do John Lynch, Jim Lippard and Mark CC. And Sandra and Chad chime in. Karmen and Steinn as well.