Action Comics! Makes sense as a first addition... considering that Superman's first appearance was in the very first issue in 1937. Changed everything.
This superman, is much more akin to THAT superman, and less to the one we're used to today. He's now (and again) spry, fearless, has no real idea what he's truly capable of and out for social justice! Grant Morrison and Rags Morales spearhead this series (with a little help from some friends).