I came across this german magazine ad for Budersand, a hotel & spa, that used a clever play on imagery to get people to stop and think.  While the execution itself is being debated on adsoftheworld.com as to whether it’s good creative or not, this ad serves as a good example of how easily creative elements used on a magazine print ad can be re-purposed for a direct mail piece.  The below screenshot shows a selective cropping of the original 8.5×11 ad:

Original print ad by KAT DESIGN

Here’s the same ad cropped down to dimensions that would be easily ported to a postcard asset:

Recropped mock up (Note the tagline is something to the effect of "Too good to be true?") Credit for original artwork to KAT Design

Never mind the fact that the agency & Budersand themselves should have an active loyalty program for VIPs that includes direct mail, but the ease with which direct creative can be created by using existing artwork is seldom talked about.  If the artwork fits with the branding objectives that you have for your direct mail, then maybe there are some diamonds that are already on your shelves (or in your network folders).