Of the different free wiki providers out there, pbwiki at the moment is still my favourite, as it is powerful yet easy to use and by choosing education when signing up, there are no ‘dodgy’ adverts appearing.
One problem that it used to have, was the way of giving people permission to edit – if you wanted the wiki to be private and only visible to a few people (e.g. your group of learners) then it was hard work putting in all the learners email addresses, or getting them to set up accounts, etc.
However – I am just setting a wiki up to use in a training session tomorrow and notice that they have streamlined the process, so that you can quickly create temporary user accounts for the wiki, and it will create passwords for you, and print it all out on a sheet, that I can then cut up ready to give to the learners. For someone like me running training sessions, where I often don’t know in advance who will be attending this is brilliant.