Today I ran a workshop at the Southampton Maptime meetup. It covered Leaflet for begineers.
The slides are available, and the material (including the slides) I used can be found in this git repository, and is also available to download as a zip or tgz archive.
All in all, I think the material was well recieved. I was quite glad at the amount people deviated from the examples that I gave, as that really showed that there was understanding.