...Also, I am easily tired of "girl + gun + mecha - underwear" type of artwork...

Well there ya go buddy. *wink*
[edit for critiques]
CheckworthI like the mood. I suggest you utilize the palette more to separate the character and the background. A bright character on a dark background, or the opposite. Outlines are another option, but I think that piece works best without them.
Ryumaru & SkurwyFinish! Why on god's green earth would any sane person not finish a beautiful piece like that?
RyonaLove the pose and character. She seems to be suffering a bit from tentacle hair like the kunoichi did.
KrenDon't be afraid to throw in colors into the skin tones other than the obvious yellows and oranges. A lot of the time the value of a color takes precedence over the actual hue, allowing a lot of room for experimentation
MoDThe bottom box looks okay, but the perspective lines on the top box seem to be meeting at a point somewhere
above the horizon, which may explain some wonkyness in it's appearance.
glidingI'd suggest you figure out what the pants are made of. If they are something shiny like leather, then make it clear that they are shiny with thin bright specular highlights. If they are made of something non-reflective, then block out the shades and avoid anything that looks like a sheen. The head and arms, for instance, clearly communicate the surface of the skin. The pants on the other hand, leave me scratching my head.