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.
Each team member explores one topic in depth in a series of 1:1 talks Source: Thorsten Kalnin
Each participant writes down one topic they want to explore, i.e. something they'd like to change. Then form pairs and spread across the room. Each pair discusses both topics and ponders possible actions - 5 minutes per participant (topic) - one after the other. After 10 minutes the pairs break up to form new pairs. Continue until everyone has talked to everyone else. If the group has an odd number of members, the facilitator is part of a pair but the partner gets all 10 minutes for their topic.
Get a sense of everyone's position and reach consensus Source: Nick Oostvogels
When the team can't decide between two options, create a big scale (i.e. a long line) on the floor with masking tape. Mark one end as option A) and the other as option B). Team members position themselves on the scale according to their preference for either option. Now tweak the options until one option has a clear majority.
Gauge participants' satisfaction with the retro on a scale from 1 to 5 in minimum time Source: ALE 2011, Corinna Baldauf
Put sticky notes on the door with the numbers 1 through 5 on them. 1 is the topmost and best, 5 the lowest and worst.When ending the retrospective, ask your participants to put a sticky to the number they feel reflects the session. The sticky can be empty or have a comment or suggestion on it.