Cache images on iOS device

I know Indigo Touch already does some form of caching of images on the device for control pages, but i find often it's having to refresh images that haven't changed. What'd be great is if we could actually load all those images into the app (either automatically or even via the 'file management' option in itunes if you can call it that) so that it's not constantly using 4g data allowances for images that don't change.