Mama, Dada, Up, Down, Moo, Dig, Duck, Apple, Banana, Yellow, Blue, Flower, Bye-Bye, and Ball.
"Apple" is by far his favorite. Lori's theme in the kitchen is apples, so there are apples on lots of the things in there. He walks around the kitchen pointing at everything saying "Apple! Apple!". It's really amazing. I suspect that this will stay a lot of fun until he learns how to say "what's that?". I've heard that gets old real quick. :)