With the new A123 and LiFe RX batteries (which eventually most will be using) the only issue I see is the flat voltage drop until its almost too late. Someone needs to develope an item similiar to the volt watch in size, only its a mah usage meter/readout (like many chargers have) with a resetable nonvolitalile memory. And heck why not put a volt reading on it also.

Then you might know where you stand.