Things Isaac is doing that he didn't used to do:

grabbing toys
batting toys
laughing
smiling much more
crying for no apparent reason
soothing himself back to sleep in the middle of the night
falling asleep on his own for naps and at night (it's rare but it happens)
splish-splashing non-stop in the bath
laughing in the bath
screaming when we used a different soap from the smell
washing dishes and vacuuming (ok, I'm dreaming here)
fitting into his carrier like a big boy, no more silly infant insert needed

Impressive, huh? :)