Boob jobs aside, there are non-surgical (and free!) ways of enhancing what Mother Nature gave you; like all Mothers, she plays favourites with her daughters - but it is pointless to complain.
This is a prime example of what I call the Japanese cleavage enhancing pose (I swear this image is somewhere on my blog, but I can't find it).
The 2 parts of this tactic:
1) Bend forward (and down), so gravity gives you a boost
2) Subtly use your upper arms to squeeze inwards so your mass is consolidated
Notice how here one's arm can serve as a subtle pushup bra