Sign language for the pre-verbal
RJ used sign language to "talk" to his pre-verbal kids (and let them reply):
Start learning and using some ASL (American Sign Language.) Children have the ability to grasp language before they have the muscle control or brain development to speak, and teaching them some signs (like milk, potty, more, food, hot) will allow them to communicate their needs, cutting down on frustration and the ensuing tantrum. We just use "The Joy of Signing" to look up anything we think our daughter might want to express and start using the sign ourselves whenever the topic comes up. I've read that children tend to start using sign around 8 months or later, so just keep using one or two signs until they start to reciprocate, then you can expand from there.
It's also cool to be able to communicate non-verbally with your children in public, or from a distance without shouting, letting you both conspire to slip away for some nursing or a potty break without broadcasting your plans to the room!