I've reviewed sports bras for the well-endowed ladies, but what about for those of us with a bit less va-va-voom?
I recently purchased the Lululemon Flow Y Bra II and I am in love with this top. This great little bra is the whole package. It provides good support, the mesh back insert provides maximum ventilation, and the racer back shape allows for full range of motion without irritation (i.e. no chafing). Not only did the bra pass the yoga test, it also passed the ultimate bounce test: running. The colors are super cute (mine is yellow with white polka dots) and it even comes with light removable padding, which keeps things discrete even when it's a tad "nippy" in the gym.
I've been wearing mine so much that I've gone back and bought a few more. At $42 it's a little steep, but a good sports bra can be hard to come by and this one is worth every single penny. Go try one on at a Lululemon store near you.