i know in MGS1 when u look throught the vent and see meryel she is doing pushups or somethings and if you go back and then back to merels vent again she is doing something diffrent
MGS2:
when ur in a locker and therse a picture of a girl and then you hold R1 it makes a weird sound (:S)
And in mgs3 there are little scenes where you hold down R1 (without it telling you) and you see little diffrent things eg. the sorrow
but so far i have in MGS4
The first scene where you see screaming mantis (and all the other BB's owning those militia solders)
when it says hold L1
hold it and look left and you will see Phyco mantis (Best villan)
use the mk2 pistol (Tranq Gun)
on all the beautys (Laughing,screaming etc)
and you get there face in face camo
but that all i have so far
your opinions?