App Chef allows you to create universal binary apps by combining two or more apps. The first app (the actual app, not the binary in the ./Contents/MacOS/ folder) dropped in is the app that will be over-written after clicking on the "Create" button. This way you don't have to create a new app folder and put your resources, plist, and more back in. It supports Intel 32, Intel 64, PPC 32 and PPC 64 architectures. App Chef itself is a universal binary that supports both 32 and 64 bit OS.
Tested on Snow Leopard 10.6.8 and Mavericks 10.9.3.
Download App ChefI wasn't able to sign this app due to what it does. I will see about possibly using a temporary entitlement and see if I can sandbox it then.