Share 'What ISO do you use the most (in given lighting situations)?'

I'm wondering what other peoples opinions are on this. I recently took a lot of shots for a friend for her business and I tended towards using ISO100 for pretty much the whole lot (using flash bouncing for lighting as needed). Of course, when I passed these pictures on to a friend to have a fiddle with (read as: edit into being a more interesting picture =P), he noticed immediately that I was sh…