I have a Handspring Visor handheld, it has the Horus Vision ballistic program in a chip on it and was $260.00 I think, from Horus Vision.
It works in the field as quickly modifiable chart. It has the ability to account for inclination angle as well as all the normal features a ballistic program contains.
It does not produce a chart displaying MOA correction at various ranges, rather you enter into it the specific range down to the yard and it gives you the amount needed to dial in to your scope in MOA or clicks, one or the other.
You can enter into it the wind direction and speed too, it will display the correction needed for it too.
It has a function for leading the animal if it is moving also, enter in the speed and direction (left or right) the animal is moving and it figures the lead correction too.
It works out to 3000 yards if I remember correctly.
One thing I find nice about it, its ability to give you a correction at the specific range needed, not just to the nearest point on a paper chart you have which are usually 10, 20 or 50 yard increments.
I think Ric may have the same unit too. He may have used his a little more than I have and might elaborate, I've only used mine with my 416wby and 300 Ultra out to 800 yards so far and they follow the program so far.
It seems the SMOA (shooters MOA) setting as opposed to the TMOA (true MOA)setting follows the Oehler ballistic Explorer program I have exactly.
My actual trajectory has followed the SMOA beyond 400 yards and not the TMOA for what it's worth. I havn't looked into it further to see why though.
Horus Vision home page