755 - Owner has all, and Group and Other can read and execute
700 - Owner has all
644 - Owner can read and write, and Group and Other can read
600 - Owner can read and write
And, if you're using non-trivial user groups:
775 - Owner can read and write, and Group and Other can read
770 - Owner and Group have all, and Other can read and execute
750 - Owner has all, and Group can read and execute
664 - Owner and Group can read and write, and Other can just read
660 - Owner and Group can read and write
640 - Owner can read and write, and Group can read
777 and 666 are rarely used, except in /tmp.