As people have pointed out Catman has been around for a while actually, and he's pretty much as described. Typically he steps in and kicks a lot of butt, and then steps out. He's done things like save Gotham vigilantes during prison uprisings and such. He's also been one of "The Secret Six" and other assorted big moments. He's a character that works because he has a decent amount of cred, but isn't overused, so people tend to forget about him.
http://en.wikipedia.org/wiki/Catman_(comics)
Oh and if you pay attention he's been around since the 1960s, and the writers have defined him as bi-sexual (since the comments about homophobia were int he article).
The big question is whether or not Catman could carry his own book, or otherwise see more frequent use, I'm not sure about that to be honest. All political arguments for it aside, he's a character that works best when he's not overused nowadays as I pointed out.
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The She-Punisher also existed, as a limited "what if" at one point if I remember but I don't remember much about it. Punisher 2099 also featured a renegade "pleasure doll" (shades of Blade Runner) called "Vendetta" who became his partner, she covered a lot of the same territory.
To be honest with you though, I don't think there is a problem with women in comics being too "soft, nice, and submissive" for the most part, and it hasn't been an issue for a long time. Indeed it's become something of a trope/ongoing joke that a lot of sociopathic behavior gets ignored when perpetuated by women in comics, especially with creators who go out of their way to make them do the whole "hardass" thing. For example if you start going through the list of say female characters in "Wildstorm" which WAS a major imprint for a while, your going to run into characters like Zealot, Jenny Sparks, Maxine "Ladytron" Manchester (absolute psycho), Flint, The Engineer, Swift, Nemesis, and scads of others. One of the old comments about the general "Wildstorm" formula was that as a general rule the guys were typically the "nicer" ones on the team, the ladies would feed you your own spleen (though exceptions do exist). I mean consider that one of Wildstorm's Heroines was Rose Tattoo, who is literally the spirit of murder given human form, she was an active duty member of both Stormwatch (under Bendix) and The Authority at various times. Trust me, Rose is worth a few million girls with guns acting like The Punisher. Of course then again you DO have "The Dirty Pair" which was published by Adam Warren under the DC label for a while if I remember (albeit in it's own universe), The Body Doubles (who have had their own book, even if they are villains a lot of the time... they were created by Dan Abnett in fact who did a lot if hardcore Warhammer 40k stuff like the Eisenhorn trilogy), and numerous others.
One thing to also understand when it comes to comics is that one problem a lot of people have also mentioned is that female characters rarely wind up being held responsible for their actions the way guys are as well. This is a big part of why so many female characters have been able to move back and forth so easily between the hero and villain label. For example "Harley Quinn" within the comics continuity has worn the hat of villain, anti-hero, and straight out hero at various times depending on her relationships at the moment (her arc is a bit different than the cartoon version, though it usually goes back to a familiar status quo for at least a while), Harley is a genius (despite how she acts) who has committed numerous acts of mass murder, and yet other than a few side comments about not entirely trusting her, on a few occasions it's otherwise been a comparatively easy transition at times, when logically it shouldn't be. Catwoman is another example, even though she doesn't kill many people, she steals, double crosses, and has left dangerous things in the hands of people out to do really bad stuff with them, and yet other than a few side comments, everyone seems more or less willing to just let her put on the white hat... I'm sure others can come up with other examples of the trope. In comparison a big part of what makes "The Punisher" what he is, is not just that he kills people (lots of characters in comics do that nowadays), but that the magnitude of what he does is not forgotten and taken more seriously at least in relation to him. Nobody likes, or trusts, the Punisher, and the odd things is he plays it "straight" by vigilante standards more than most heroes, he's not a deep guy, and that can in some respects be an advantage. Indeed during "The Secret War" when his alliance with Cap falls apart due to The Punisher not being willing to forgive villains due to the situation of the moment, part of that is pretty much that Frank very much stays on mission and doesn't compromise. As a general rule, to do a female punisher, you need more than a girl who kills people, you need a girl who kills people, and for whatever reason is held unusually accountable for the deaths by other characters, and generally gets crap for it (sometimes hypocritically when dealing with other lethal heroes). As a general rule the only female character off the top of my head that seems to ever be held accountable for anything, and have it stick/taken seriously other than a few comments is probably The Huntress.
Generally speaking though, I do not think a female Punisher would impress the people who "want it" as they would probably see it as being anti-feminist since the idea is pretty much to give the character crap, and view it through the eyes of standards that might be "realistic" but oddly might not exist (or be mentioned/harped on) with any other character in that universe. The Punisher is basically Mack Bolan (old character from vigilante action novels) in a super hero world, meant to draw a parallel, a character who oddly isn't as relevant as he once was as the standard he acted as a counterpart to ("realistic" action hero/vigilante in a world of super-heroes with exaggerated codes of ethics) no longer exists to the same extent as almost every character out there has had some kind of "darker, grittier reboot"
over the last few years. If you just want a female character who acts like a hardcase (but does the right thing) and kills lots of really bad people, oftentimes in alarming ways, there have been plenty of those out there.