Andy Stanley's talk about Systems really connects with me. If you haven't heard it google it now and soak it up! In that talk he says "Systems create behaviors" and I couldn't agree more.
We have a system for curriculum. We create a set of discussion questions with Scripture that we post online weekly as a .pdf file. Because it's simple, affordable, and accessible group leaders download and use it on a nearly weekly basis. The system created a behavior: the weekly habit of downloading curriculum.
Recently at JourneyChurch.tv we mixed things up with our curriculum by removing the discussion element from the weekly curriculum and inserting a 60 minute mission activity. So our leaders habitually download the document and then follow a mission "recipe" with their group rather than discuss a topic. We're doing this for 10 weeks. You can see this curriculum at http://www.journeygroups.tv
Why are we doing this? To leverage an effective/exisiting system and get groups to experience mission. This modification to the system is having a great effect on the behavior of our groups! They are becoming more missional.
What missional systems do you have in your small group ministries? I want to steal as many good ideas as I can so please spill the beans!