"build it yourself", using "PlugMold", from wire-mold corp. Available at most of the home-improvement superstores. (this is the permanent wiring stuff.)
Radio Shack used to sell exactly what you're looking for, their part
61-2155 *discontinued*.Browse through industrial supply catalogs, looking for outlet strips to go into 'Rack cabinets'. Be prepared to pay $100 or so.
*Somebody* -- AHA! here it is! "Improvements" sells bundles of 'shortie' (ie. 1-foot) extension cords, for exactly that use. (plug the wall-wart into the extension cord, and the extension cord into the strip.) my catalog shows a package of 5, for $13. Their item #238359There are also "strips" (they're not really strips, but biggish rectangles) made expressly for wall-warts, have the outlets located 'sideways' to typical, so that the xformer hangs off the side of the thing. And have several inches of space between the outlets, to accomodate the width of the xformer. Check a biggish hardware store and/or the home-improvement stores.