What I don't know about flash meters would fill libraries, but it occurs to me that digital photography is instantaneous, so you can proof your flash immediately and reduce the flash if necessary using your camera's flash compensation feature (assuming it has one). Also, your camera may have a built-in point or set of points where the exposure compensation is targeted. Maybe correct flash exposure is as easy as targeting these sensor points when you shoot.
Finally, you might find that neither your flash nor your camera is able to compensate for a subject that is too close or too far away. No amount of metering will enable you to light up a subject that is beyond the range of your flash, or to not wash out a subject that is too close.
If I'm missing the point, that wouldn't surprise me.