Here's a nice write-up on batteries and why you should never fully discharge them (cell reversal).
As for the question about how to safely discharge them, just let your laptop do its job. Learn patience
As a practical guide, discharging should not exceed 2x of the battery's capacity (according to Panasonic). So for a 3000maH battery, you would not want to exceed 6 amps (6000ma).
Radio control models exceed this rate all the time, so this may just be a Panasonic thing (but by the same token our batteries don't seem to last long either).
Oh, and never, never recharge a hot battery. Wait for it to cool, it harms the battery if you let it overheat.
Here's the Panasonic NIMH design guide (very good, short read)