ConvertExtension
So, what is it?
ConvertExtension is a carbon application which lets you change the Mac Creator/Type code of a bunch of files with a given extension at the same time, even recursively for a bunch of files/folders. You don't type in the desired Mac Creator/Type code, since you often don't know what that is. Instead you drag a file that already has the correct Mac Creator/Type into the window, and the program will use that.
Download: