You can also load programs over the audio port. Apple IIs originally shipped with tape players, and data was loaded to and from cassette tapes. I believe there are several programs that let you send apps over the speaker port on your PC or Mac to your Apple II.
I believe it's an option in ADTPro.
I think some people have even made MP3s of various programs which you can load up on your phone or music player, then "play" them to your Apple II.