I’ve mentioned before how insanely useful it is to know something like the [NATO Alphabet][1] (where people say “Alpha Bravo Charlie” instead of ABC). Sometimes you forget a letter, or are just too slow to feel comfortable saying it, well fear no more [there’s now an app for that][2].
No clue how useful this will be to people, but I downloaded it.
[1]: https://en.wikipedia.org/wiki/NATO_phonetic_alphabet
[2]: https://itunes.apple.com/us/app/spelling-alphabet/id499351638?mt=12