[Winga]

For example, an octahedral complex, the eg* orbital is counted as having a little bonding character when it is filledwith pair of e-s.

Also, why atomic orbital is become extra stable when it is full filled or half filled?

[Winga]

For half-filled or full-filled AO, "it becomes stable", does it mean the atom is stable or the atomic orbital is stable?

[Mitch]

Yet an other reason why I hate the word "stable".

Half filled orbitals are typically perpendicular to each other and don't interact with each other, so you can put 1 electron into each orbital without any serious problems. Once filled however, it takes more energy to fill them up because is costs energy to pair electrons in the same orbital(Who wants to be sharing an orbital with an other negatvie guy?).

People say having all the orbitals filled makes it more "stable", the stability they refer to is not energetic stabillity but chemical stabillity since it doesn't want to give or receive an electron.