Mimic, liar, and agressive (doesn't want to be left behind). Yup, that's our current Ginny. In fact, in light of that, I've suggested, and had my elder daughter shoot me down, that Ginny got a bit more in the Riddle exchange than just a near-death experience. Don't those traits belong in Slytherin House?

I don't see these traits as 'belonging' to Slytherine House; on the contrary, they seem to be very 'Gryffindor.' The Slyth idea revolves around ambition, true, but not aggression or lying. If anything, the Slyths would be good at persuasion and negotiating and diplomacy. Gryffindor House is the house of aggressive warrior types. Ginny fits in perfectly.