When participating in meetings, have each of the participants take on a role other than their own - usually as a representative of a part of the organization that is not represented. This gets them to think outside of their comfort zone, and to dissent or participate in new ways. Developers can take on the "Finance" role, for example.
When a team of people with similar backgrounds enters a design discussion, they tend to focus on the same things; and tend to stray away from others. After several hours of deviating, or coming up with a great solution, they realize that it is incompatible with the other departments.
At the beginning of the meeting, assign a role to each person (in addition to their regular role). For eaxmple, in a team of developers, one of them should portray the repreentative of the sales team, and another from the finance office, and another from upper management. During the discussions, each individual can portray their role (or in fact, speak up for the member they represent that is not present) to ensure that the argument is heard.
Team members look at each problem from another perspective
Team members expand the scope of their thought processes and perhaps discover the good and bad of other departments
Final solutions are well-rounded and take into account more than the one team involved
Provides entertainment and change to normal meetings