We recently took a weekend road trip with our 20 month-old son. His normal bedtime routine includes a bath, books, and some quiet classical music in the background.
To make sure the routine was followed as well as possible, I loaded a few of his favorite CDs on our iPod and packed the FM transmitter (a Griffin iTrip). At bedtime I tuned the room’s clock radio to the transmitter’s frequency and turned on the sleep timer, then played his favorite bedtime CD on the iPod.
It worked like a charm. He went to sleep on his own without fuss, despite being in a strange room and a different bed.