In search of icon help

I've gone on a bit of a Classic spree on my iMac, replacing most of the system icons with ones that fit a Classic theme.

I hate having some icons sitting out like a sore thumb though, is there any way I can change the icon for an entire file type? For example, the icon for an unmounted .dmg file or a .zip file.

Also, does anyone have a Classic style Mail icon or (even better) a set of as many Classic icons as possible?