Melfina stomping on and killing the evil mind-control cactus.
Harry makes another advance towards Melfina with the attempt to kidnap her. He had her in his arms and then she slammed her fists into his back to make him let go of her. Later, in cyberspace, she force-feedbacked Harry's hacking attempt so damn hard that it blows out his arm. Considering how scared she was of Harry (its justified given how Ax-Crazy he is) it was awesome seeing her reject Harry and constantly refuse his advances.
Suzuka completely emasculating Gene by nonchalantly nabbing a very dangerous and high-paying bounty out from under him the ninth episode. This was a response to Gene defeating her in her first appearance (grabbing her kimono belt and basically stripping her as the two ran for her sword).
Suzuka slashing a bus with her katana on the episode that introduced her.
The Crackerjack episode.
A dual CMOA for Suzuka and Aisha when they track down and kick the ass of Crackerjack's crew while simultaneously tipping Gene off on his Red Wire Blue Wire dilemma, thus saving the entire city.
Melfina gets one as a Crowning Moment of Funny when she replies to Gene's goading of Crackerjack, utterly deadpan "You know, you really should not aggravate the terrorist."
At the end of the same episode, Gene crashing the Outlaw Star right into the space station, jumping out and KO'ing Crackerjack with one punch.
Basically everything Hilda did was awesome, but her last was probably her best: realizing that she was not going to make it, she immediately grabbed ahold of The Dragon, gave a badass "Facing the Bullets" One-Liner, and then blew the both of them up with a bomb she had hidden in her tooth. "Outlaws never go down easy," indeed.
The first part of the first episode. Enemy fighters clamped onto your ship? All your weapons gone? Activate the Sub Ether drive (the Outlaw Star universe variant of Hyperspace) just as the bastards are getting cocky, and obliterate the fighters.
Shimi/Lei Fong effortlessly taking out Jim, Suzuka, and Aisha when they dare to get between him and his duel with Gene. It's made all the more awesome by him being the Badass Normal of the pirates and yet possibly the one who came closest to beating him.
Jim singlehandedly taking out a spacefaring malcontent... even though he killed his almost girlfriend accidentally.
The final battle, with Gene and his crew battling a god-like Hazanko in both cyber space and with their ships, the Outlaw Star and Geomancer both getting massive, giant sized upgrades. It ends with the Outlaw Star back to normal size and Gene flying right through Hazanko's head like a bullet.