Adin is up to some cute highjinks as well. I can prop him up on the couch and give him a toy and he'll hold it and play with it for a while. Yesterday he had a funnel and I showed him a stuffed duck. He was excited by the duck (I guess it's more fun than a funnel!) so I handed it to him. Adin set down the funnel, reached for the duck and then brought his hands together to play with it! It's definitely the most complicated action I've seen him do.
When I put him on his tummy, usually he tries to roll over right away. Sometimes, I can sit next to him and put a little pressure on his shoulder so he can't roll over. If I put a little toy in front of him, he'll reach out for it. That's a big deal too!