Is it leaking on the ground from anywhere? did you recently fill it up? there's an o-ring-type gasket that will leak sometimes where the filler neck goes into the gas tank.
Right now my car smells like coolant and transmission fluid. If this smelling like different liquids thing keeps up it should smell like gas before too long.
I figure it only has gas and gear oil left as possibilities. Maybe washer fluid too.
If it starts smelling like gas and I figure out what is causing it I will reply back in this thread.