So R' Katz at CSAIR mentioned that he'd been thinking about a HaMalka (The Queen) megillah and fiddling about with it and only getting partway...
...and I, being a Total Nerd with Mad Leet Computer Tikkun Skillz, decided to give it a shot. And I did it. HaMalka megillah, looking pretty sweet.
Of course, the thing about HaMelekh is that King is allegorical for God, and since there isn't any God in the Megillah, the HaMelekh is a compensatory move. HaMalka obviously takes away from that, so if you are doing HaMalka you have to read it as riffing on the HaMelekh/God theme, rather than as a Stomping Feminist theme.
I suspect most people would assume it was a Stomping Feminist thing ("You changed HaMelekh? Don't you realise that HaMelekh refers to God?! Sheesh, you indulge your ridiculous ignorant feminism and just make yourself look stupid..."). One would get tired of explaining that no, one is very well aware of HaMelekh, and HaMalka retains the concept of sovereignty with its hints of God but adds a feminine aspect, as to say "My relationship with God is informed by my being female, and I can engage with ritual on that basis, and it is kosher and it is joyous."
You see I think people might not understand that. It makes me wonder whether alternating Melekh and Malka on the column heads would be a better move, but on the whole I think the feminine riff is worth it.