I'd like to see the MegaCell batteries be two blocks tall, so you could make realistic looking batteries. The reason being, I had an idea for a build that involved having them mounted in a thing in the wall, with extra batteries stockpiled for rotation. You could also do a horizontal version of the battery texture, so we could have piles of batteries stacked in our warehouses.

This would also give another use to the Ender Offset Wand, since you could adjust which block was the 'top' for your builds, without having to build in a certain position.