[sebazzz]

Similar story here. I wrote programs in TI-Basic to help with some exam questions, and wrote summaries in TI NoteFlio. I ended up getting so many few-euro donations for them from everyone who used them. 30 minutes before the exams, exchanging these things over the TI-link connection.

Of course, nowadays all these TI calculators have exam mode, which blocks the internal memory and a bright LED to indicate this mode is enabled. And the older calculators, with practically the same feature-set (TI-83, TI-84) are now forbidden (should clarify still the same TI-8x calculators are allowed - but only if they have exam mode). Nothing is fun anymore these days.