Had a site recently that was complaining about bandwidth consumed by request for apple-touch-icon* files as described here:
The customized 404 page on the site was using about 55K bytes for each request. I added the following rewrite rule:
RewriteRule ^apple-touch-icon(.*) - [R=404,L,NC]
This results in about 500 bytes per request or a 100 fold reduction.
Of course a nicer solution would be add pretty touch icons to the site!