Here at Devex we have one week sprints and a retrospective meeting every friday. We use post-its to write down our items and put them on the whiteboard. But somehow we were not really happy with that solution (not sticking properly to the whiteboard, a non-ecological feeling, running out of certain colours, ...) and looked for an alternative.
Next step I laminated the coloured paper:
Out of one DIN-A5 sheet I cut 6 post-it-sized squares and did the same with the magnetic foil:
Then it's just putting them together and you are ready to go (magnetic whiteboard required)!
Here's a picture from one of our recent retrospectives: