An intuitive software erector kit targeted at people new to programming, but with enough potential to stay useful once they've learned, inspired by HyperCard.
These could just be simple numToChar()-style functions, or a postfix syntax like #42. Ideally these would be cross-platform, but that would preclude using Apple's CommonCrypto.
Functions for encrypting a string in a secure way. I.e. give a string and a password, turn into gibberish/turn back. Maybe use LibreSSL for that?