Pair participants; have them interview each other for a couple of minutes and then the partners introduce each other to the group, i.e. name, time with agency, and then usually something slightly more personal: what the person expects from this meeting; what the person really hates about meetings; or what the most interesting part of their job is, etc.
Participants form pairs, interview, and introduce each other. However, to make it non-threatening, they have to find out something about the other person that no one else in the room knows!!! This usually ends up being quite hilarious and 'frees' up the big group.
If there are more than 20 people in the room, get them to share the information in smaller groups to save time, and then ask for one of the most unusual things from each group that was discovered about one of their members.
This is a useful activity if participants have been strong competitors.