To bad you can't spend around 16k and get this:
The Scion TC. Pretty cool car.
However, since you're dealing w/ the 15k budget...
It really depends what you're looking for in a car.
If you're looking for gas mileage, get a Toyota Echo. My girlfriend has one, its a bloopy little car, but 43mpg on average, and is actually very roomy inside.
If you're looking for a sportier car, I'd say go for the Mazda3.
However, if you can get a car that is like a year or two old, and not brand spanking new, you really could get a few great deals.
Don't forget about Hyundai either. They have a great warrenty, and the Tiburon is a pretty impressive car looks wise. And the GT model is pretty nice. Though, at around 16k, a bit to much.