Lilian Soon of xlearn is superb when it comes to using mobile phones with learners, and one technique that she has developed is creating a series of small image files, which you then distribute to the learners phones, and if they flick through them in sequence they have a learning object. Lilian has created a couple of video clips showing how to do this (by using good old humble paint) and what the end product looks like.
The first video, shows the end product
and the next shows, how this was created.
Another possible variation of this, would be to have images that show a sequence that has to be followed as a guide, so in say plumbing, for people learning the correct order to do thigns when doing a solder joint, a pictoral guide (that they then carry round with them on their phone) could be useful to some people, until they have learnt the technique fully.