Good point, well presented. You've actually sparked a nasty thought on that subject.
Posting the downloads in zip files is ok for uncompressed images that won't display in the browser (tif, psd etc.) but it will add to the size of jpegs which are already compressed?
I'm thinking I need to pop up the full size images of photo's etc. for a right click download and put stuff like clip art (wmf files) somewhere else to download as zips...hmmmmm