In order to retain full ownership of the files and directories but give access to Apache, one wants to use the ACL feature built into Mac OS X. By using sudo chmod -R +a '_www allow read,write,delete,add_file,add_subdirectory,file_inherit,directory_inherit' <dir>, you’ll grant the required permissions to Apache while keeping everything else intact. The file_inherit and directory_inherit will ensure that the ACL is applied to new files and directories.

For more information on ACL‘s, you should read a blog post titled OS X ACL’s from the Commandline posted by ideocentric.