Biology:
Just know HW equations
Chem: Rate laws & equilibrium are your friends. So is stoich
Orgo: None, really
Physics: Kinematics, dynamics, momentum, pressure, torque, etc. etc. Pretty much standard stuff.
It's hard to call down to the dot what formulae are put on the MCAT. Best bet is to understand the formulas (afterwards, memorization comes pretty easily, and if not, don't sweat it too much).
The above link was an excellent resource for a guideline to what formulae should be understood and possible memorized.