I was in an education programme for unemployed where a very unorganized (but vast in numbers) sick-in took place. It had no connection to any issue on the programme as such but depended on the fact that we in the kitchen class was not allowed to see the world cup games. So almost everybody called in sick on Swedens first game. This resulted in a threat that we would be cut from the education if we also called in sick for the second game. I think I wrote something short about it in the Lernia text.
On another level I was at a bakery where we refused to do some work and claimed it was a health risk to it - these forms of actions is far more common I guess.
call centres aside has anyone had much first hand experience with sick ins in a workplace that isn't union certified??? I've heard a lot of people talk about sick ins, but I just have some difficulty seeing it work in an unorganized workplace, mainly because most non-union workplaces I've worked at had un-official punishments (like having schedules drastically reduced, etc.) for people who phoned in sick more than once a year or so and also required doctors notes based on management's whims.