I can actually recall such situations - When we had to do group work at school. I always hated it. I am not very confident in my decisions, but at the same time I often have a very set image on how I want things done, so I often used take charges in these situations - also, because no one else would and we would not get anything done otherwise.
However, that's really the only situation I can think of. Usually I try to avoid taking charge. Don't even want to have to decide what's for dinner.

You should hear our dinner plainning converstions:
"What do you want for dinner?"
"I have no idea, whatever you want"
"I also have no idea, you deicde!
"No, I don't want to decide, you decide"
"isnt't there anything you want?"
"Gosh, just make something, I'll eat anything!"
"No, that's not true, you eat almost nothing at all!"
Me and my husband. Every day.
By the way, any Final Fantasy Players here?