Here's a running list of things he's said or sounds he's made.  I'm dividing this list into 2 sections.  One is for general "sounds", but the other is for words and phrases which he is saying with clear intent and understanding:

Deep and Meaningful:

• "Nice" (George uses this appropriately, and only as an adjective.  He says "nice" when enjoying a treat, music, or interactions that he particularly enjoys).
• "Me?" (this he says in direct response to a question or statement.  For example, if I say "George, what are you doing?" He'll look up at me as ask "Me?")
• "Whatcha doin?" (and he wants an answer, not just any response.  He'll repeat it over and over until you tell him what you are doing.)

General Sounds:

• Laka's laugh (Laka imitates me.  George picked it up from her).
• our canary's whistling
• The opening notes to "Un Bel Di " - the aria from Madama Butterfly (but instead of the correct lyrics he just sings "laaaaaaaaaaa lala lalaaaaaaa" and so on).
• "La-la-la-la-la" (the chorus to the song "Loving You Is Easy, Cuz You're Beautiful".)
• "step away from the vehicle, sir" (Sounds like a police officer talking through a public-address horn. His previous family(s) must've loved cop shows)
• "Brenda!  Brenda... come to bed now"
• "Make a pot!" (he's imitating Laka, who has been practicing saying "Laka, make a potty" but hasn't got the second syllable in "potty" down yet.  Interestingly, he just says "make a pot", but omits her name.)
• "peek-a-boo"
• water dripping
• "George is a GOOD boy"
• "Step up"
• "Come on, George!"
• "Ok?  OK?"
• "Huh?"
• "Hello!  HellllooooooooOOOO!" (Australian accent)
• "Hello!" (American accent)
• "Hello, GEORGE"
• "mmmmmmmmmWACK!" (loud "smacking" kiss sound)
• car alarm (oh my... full volume and very convincing.  Thankfully he doesn't do this often)
• human coughing
• human throwing up (I could do without this one...)
•  a very convincing imitation of a human passing gas - (so convincing and "liquid" sounding that you just about want to run from the room.)