I was just thinking about a session I gave on eMarketing last night for people starting businesses. I find that people just sit and listen at the start, however as they warm to you they feel more comfortable asking questions until towards the end of the session it become an open discussion more than a presentation.
A great icebreaking idea that I got from Yvonne Adelle is to make everyone wear name tags that have their nickname on it instead of their real name.
In a large group you can get people to nominate what there current or highschool nickname was, or in a smaller group you get brainstorm and then have a vote on what you are going to call each person. This gets the group working together and also jumps starts their creativity before the workshop starts.