NARS blush in Orgasm
Every girl needs this, and it's consistently made the best products lists in InStyle and fashion magazines for ages.
The reason is that this shade works for all skin tones and looks really natural and pretty. It's basically supposed to 'simulate' a soft flush in the cheeks like the type you get after you have an orgasm. The product lasts a long time. Easily available at Sephora (among other places).
It's amazing.

This is what it looks like on the cheek:

NARS also duplicated this shade in a lip gloss (I've tried it, not bad) and also a nail polish (don't buy it - horribly overpriced and the quality is meh according to the fashion blogs). Go for the blusher. Definitely.
If you like a bit more of a shimmer - I would also highly recommend Bobbi Brown's shimmer bricks. They have them in different shades - here it is in 'Beach':

The shimmer bricks are total amazeballs. Seriously. They can also double as eye-shadow shimmer and you can dust it over your shoulders or along the collar bone or even along the back of the calves as a subtle shimmery highlight during nights out - this looks especially gorgeous with a light tan. The best part - they last forever. They also have a specific 'body shimmer brick' which is bigger and has a more subtle shimmer, designed for body skin highlighting but it's best to start with the basic brick and see if its your thing.