They offer six principles to make an idea memorable:
I came across a fun example of principle #2 (unexpectness) on a recent trip to visit my sister in Orlando. At several intersections near her house, signs were posted warning that motorists would be fined $183.50 if caught running a red light. I commented on how odd that amount is and my sister (she's so smart!) responded it's to make people talk about it. Duh! I'd read Made to Stick--why didn't I think of that? Anyways, on a later trip in the car, my husband (who wasn't there for the initial conversation) made the same comment I had. Almost a month later, I still remember the exact amount of the fine. What a simple way to make an impression!
If you haven't read Made to Stick, I highly recommend it. I had purchased the audiobook version through iTunes, and I loved it so much that I'm seriously considering buying the hardcover version for reference. If you're looking for more wisdom from the authors, you can check out their blog. They don't update it as often as I wish they would, but there's some great info there!