Well after all the suggestions -
The only other obvious one to me is Mulan - there are 2 so here's the general feel I got for how the shows are different:
1.
http://mydramalist.com/6070-mu-lan - Lighter, I don't want to say comedic but it's not quite as serious as #2. Personally I enjoyed it more.
2.
http://mydramalist.com/7807-legend-of-hua-mulan - More serious and a really slow build up to what we would recognize as Mulan (warrior/general).
In both the shows almost no one knows but I believe all the male leads for the 2 shows do know. They knew her before she joined the army.
Some more iffy ones:
Shine or Go Crazy - mainly to hide her identity from male lead. She dresses as a woman in almost every other situation.
Gu Family Book - she's not hiding anything, the male lead is portrayed as... lets say not the sharpest knife in the drawer.
Swordsman - she dresses as a male often, I forget who knows. I think it's she does it to gather information/intelligence and keep power.
Taddao Bussaya - to escape from marrying the male lead's father or something like that.
