I'm a web designer doing a site for a small car selling business, and they were asking me about designing some banner images for them. But they want some really huge ones - about 18 x 12 foot I'd say. Print really isn't a medium I'm so familiar with, so if anyone could outline the sort of size and resolution image we'd need for that, that would be great. I use istockphoto quite a bit to get images for sites - the largest on there tend to be in the region of 3,500x2,300 px at 300DPI - so pretty big, just not sure about scaling up quite so huge! Any pointers, greatly appreciated! Cheers.