I use an Excel spreadsheet. It works very well for me and I can modify the thing as I wish...
It does many of the standard items, BC, velocity, sight height, zero, range increment and some environmental manipulations (altitude, temp) and I can control the range increments easily.
The thing I like most is that I get a nice tiny printout of the drop chart(s) that I can then cut and paste into the rear Butler Creek lens cover.
And, thanks to help from Warren Jensen, it does some minor Coriolis calculation just for those that have to know that kind of thing.