Countdown
After the events of Identity Crisis, the Atom (whose estranged-wife was revealed as the villain) spent DC's missing year out of the limelight. In the weekly-sequel to the weekly event 52, Countdown, the Source Wall names Palmer as a key figure in impending DC Universe events. The search for Ray Palmer began in the Wildstorm Universe, and soon crossed onto the new 52 worlds created during the course of Infinite Crisis.
The first of these was called Countdown Presents: The Search for Ray Palmer: Gotham by Gaslight (January 2008) and was written by Gotham by Gaslight's original author, Brian Augustyn, relishing his chance to return to the world he had created. The story saw Bob the Monitor accompany Jason Todd, Donna Troy, and Kyle Rayner (the latter three inhabitants of "New Earth") through the multiverse in search of multiuniversal counterparts to Ray Palmer. The group stopped on Earth-19, the Earth where the Batman of the earlier two Elseworlds storylines acted. There, they also encountered this Earth's counterpart of Blue Beetle and Man-Bat before they went to the next Earth for their continuing search.
Their search would take them to worlds populated by characters from other Elseworlds stories, including those seen in the Batman & Dracula trilogy (Earth-43) and Superman: Red Son (Earth-30).
Read more about this topic: Gotham By Gaslight