Set up a 'retrospective mailbox' at the beginning of the iteration. Whenever something significant happens or someone has an idea for improvement, they write it down and 'post' it. (Alternatively the 'mailbox' can be a visible place. This can spark discussion during the iteration.) Go through the notes and discuss them. A mailbox is great for long iterations and forgetful teams.
Hand out pens and paper. Pose the question 'What if the company / department / team was territory? What would a map for it look like? What hints would you add for save travelling?' Let participants draw for 5-10 minutes. Hang up the drawings. Walk through each one to clarify and discuss interesting metaphors.
Divide a flip chart into boxes headed with 'Start', 'Continue' and 'Stop'. Ask your participants to write concrete proposals for each category - 1 idea per index card. Let them write in silence for a few minutes. Let everyone read out their notes and post them to the appropriate category. Lead a short discussion on what the top 20% beneficial ideas are. Vote on it by distributing dots or X's with a marker, e.g. 1, 2, and 3 dots for each person to distribute. The top 2 or 3 become your action items.
A good debriefing deepens understanding, learning and sharing. Preparation: Download and assemble the Debriefing Cube and cards.
During the retrospective, roll the cube. Then draw a card from the category it shows and use it to prompt a discussion. Repeat as time permits.
This will broaden your debriefing options and is especially great for groups without a facilitator to enable them to effectively debrief on their own.