The online ballistics program at The Best of the West
will build a drop chart with corrections for air density and incline.
Truthfully, the systems real improvement is in the calibration of a "True BC" number that allows a shooter to build an accurate BDC turret for alternate air densities. Just like the previous poster discussed. Just use the correct turret. I personally, like using the rule of thumb I posted earlier-anything to eliminate a card to carry in the field.
The second feature that really gets over looked is the wind hold MOA numbers that are also on the elevation turret. When you dial your range, the turret tells you how much hold for a 10 mph wind. I think wind is the most overlooked variable that effects ethical shot placement, and this system makes it very simple to keep track of. Now if we just had one of those wind "lasers" to measure wind down range...
This BDC is only half the system I originally put together and applied for patents on. The other half does account for the air density and incline--it will end the "BDC argument" for good (inside 1000 yards). Maybe by the end of 2010 we will have this final piece of the puzzle in place.