When Maddy was about 9 months old, we got her started on "Baby Signing Time."
Oh. My. Awesome.
For a while, it was all she would really want to do. She would sway her arms back and forth (to sign "baby") and...well, not stop until we turned the dang thing on.
Of course, she's expanded her list of acceptable viewing material. This is mostly due to Netflix, since Netflix is very convenient yet does not offer Baby Signing Time for instant watch (grumble grumble I expect the world to be at my fingertips...grumble).
But anyway, she's learned a lot of signs and uses them regularly, although there are a few things now that she prefers to say rather than sign.
I made a list a while ago of everything she could sign. She's probably forgotten some of them by now, but there were about 40.
Here are some that she still uses regularly:
food/drink: food, water, milk, juice, banana, apple, candy, grapes, cheese, cracker, cookie
animals: dog, cat, bird
vehicles: car, bus (lately used to tell us that she wants to read the book "Don't Let the Pigeon Drive the Bus," which is her current favorite), train
other words: Dad, more, please, thank you, bath, out, up, hot, cold, bubbles, brush teeth, red (random, I know), tree
I would have loved to get a video of all of this to include on here...but seriously, you try getting an 18 month old in front of a camera to do just what you want her to do. Not especially simple.
Anyway, I'm a total sign language for babies advocate. Hopefully Maddy's lil sis likes it, too!