Aquaman/Green Arrow: Deep Target is a miniseries which, as the name suggests, follows Aquaman and Green Arrow teaming up. The opening sequence follows Green Arrow sneaking into Atlantis and confronting Aquaman in his throne room. Both their faces are obscured by shadows and/or headgear, until Arrow throws back his hood and reveals that he is Arthur Curry and Oliver Queen is Aquaman. It works especially well as both men are light skinned, muscular, blond and bearded so it isn't immediately obvious they've switched places. The cover also avoids spoiling by showing them posing in front of a sunset, so their faces are shaded but not in a way that's obviously trying to hide their identities.
The Authority: The relationship between Apollo and The Midnighter is finally made explicit right before the finale of the first arc — Midnighter is desperately trying to prevent Apollo from heading out on a potentially fatal mission. The WHAM moment is not the dialogue, but the action that accompanies it — Midnighter putting his hand to Apollo's face, confirming that they are lovers.
The Rebirth one-shot of Batwoman (Rebirth) ends with a large panel of an older, more militarized Kate Kane, who is now the commanding officer of the Colony and is leading some sort of attack on Gotham.
DC vs. Vampires kicks off when a mysterious new king takes over DC's vampire community and puts a plot in motion to take over the world. In issue #6, the most likely suspect — Joker — is found dead with all of the blood drained out of him. When Barbara contacts Bruce about this, both of them realize that the new vampire king has to be one of them...and then we get a single-page panel of Dick punching Bruce through the chest.
Dick: I think it's time we both stopped lying to our family, Father.
The final page of Green Lantern: Sinestro Corps Special. We see the inner circle of the Sinestro Corps for the first time, and it's a who's who of DC's worst Crisis Crossover villains. The biggest wham of all is that, despite the name, Sinestro is not the leader of the Corps. It's the Anti-Monitor, back after twenty years.
Infinite Crisis #3 has one when the real (Earth-1) Lex Luthor destroys the holographic projectors that are disguising his imposter, revealing that person to be Alexander Luthor of Earth-3.
The Barry Allen impostor is running through the Flash Museum, looking for something, until Wally West throws him a Flash ring. The suit "Barry" draws out of the ring is a very distinct yellow, revealing the impostor to be Eobard Thawne the Reverse-Flash.
The epilogue shows that the biography "The Life Story of the Flash", which was written in the near future of Wally's time, turns out to be have written by Wally's Aunt Iris Allen — a character that had been living in the far future but was thought dead.
In the final chapter of Shazam! (2012), Black Adam holds Billy's foster siblings hostage, demanding that he hand over his powers over the Living Lightning to him for their safety. Shazam agrees to surrender, but doesn't know how. Adam explains that the Lightning flows through family, and thanks to the Wizard's blessing, he and Shazam are connected as family. At that moment, Shazam is reminded of what the Wizard told him of the Secret Spell: family is what it can be, not what it should be. And so, with a cry of "Shazam!" Billy casts his spell right at Adam and the kids. Adam comments that he doesn't feel different. But, the following two-page spread reveals that Billy has shared his powers with Freddy, Mary, Pedro, Eugene, and Darla, together becoming a Super Family Team of Shazams.
After the climax of Static: Season One, Agent Jones is sitting in a hotel room relaying Static's escapades to his higher ups, remarking that he has enough data left to restart their plans and vowing that he'll be dissecting Virgil soon enough... only for the room to suddenly darken as he starts getting covered by some very familiar shadowy bindings while someone begins to speak in distinct purple and black text boxes. It's then capped off with a Wham Line that confirms exactly who's become a Canon Immigrant.
