While I was living on Skye, I made a few quid by running a few night classes in Spanish to speakers of Gaelic. It was a very interesting experience, as I was juggling three languages in the classroom -- I used both English and Gaelic for instruction, as each had similarities to Spanish that the other didn't, and even when neither was like the Spanish, the difference between the Spanish and English at least gave justification for why the Spanish was completely different.
I only had four people in the class (well, Spanish for bilingual speakers of Gaelic and English is a fairly limited market, isn't it? Particularly in a remote corner of a sparsely populated island) but it went well.
But one thing I was acutely aware of was the problem of forgetting between lessons if you're only in the class once a week. The solution to that was, unsurprisingly, to set them homework. But for the first couple of weeks, we did no writing, so what do you do? I sat down with a Zoom field recorder and a list of prompts and made a series of short MP3 files, each 3-6 minutes long containing prompts and responses that used the language we'd covered in class.
I never assumed I was the first to do it, and with software like Audio Lesson Studio out there, it's clear that it's occurred to others before me. One such is Ravi Purushotma, who complained in his 2006 Masters thesis and elsewhere that homework sheets have stayed the same over the years, even when in-class teaching has changed with the latest teaching fashions (ie. homework is the exception to the pattern in Decoo's lecture On the mortality of language learning methods). In the thesis itself, Purushotma proposes the usual handwavery of web 2.0 (use Twitter, write a blog, make a YouTube video etc) without giving clear directions on the how, why or when; but in another article he specifically recommends Pimsleur-like content as a method of setting homework. I certainly can't find fault with that, as long as it's covering the class material properly, or alternatively being used to teach stuff that isn't an effective use of time in class.
Personally, I've got a fair bit of use out of the software Gradint, an audio-only spaced recognition system (Wikipedia definition) created by a partially-sighted learner to make up for the lack of resources for the visually impaired. As it stands, this is only really suited for the independent learner, although with a bit of tweaking, it could be made into a really handy little homework generator. And it just so happens that it's open source, and I'm going to be trying to learn Python programming properly over the next wee while....