robin, I've read almost all of them. I got "Old Man's War" as a free download and was hooked. It is the first in a series of 4 (so far) and I read the first 3. The 4th appears to be a young adult book and the sample that I read did not motivate me. He is an excellent writer. like Asimov, Scalzi creates a universe and peoples it with interesting people. Along this line, you might also enjoy Charles Stross, another excellent science fiction writer.