Electric Vehicle Range Calculator?

I've seen one of these in the past. I think it was either a spreadsheet or a website where you can enter in variables such as the vehicle weight, drag coefficient, battery capacity, speed and elevation gain - and it will tell you how far you can go on a charge. Anyone know where I can find something like this? For that matter, maybe it would be helpful to have a topic devoted to EV calculators...

Thanks for the helpful suggestions. That Road2 program would do what I want, if it wasn't limited to the Roadster - but there's no way to input custom data for another vehicle. I think it's safe to assume they will add profiles for other vehicles once they become common.

What I was hoping to find is something that would help me estimate the usable range of the Leaf from my home considering the different speed limits on the streets here. Also I live near the mountains and since going uphill uses more energy I want to know if I could make it up there on one charge. With its limited range, these things become more important. It would be nice not to have to depend on a gas-sucking vehicle for those longer weekend trips.