I also feel like I could write a novel on the funny things my birds do!
Here are some highlights:
Milo loves her little plastic cat toys w/ bells and plastic jacks. Though the other birds mostly ignore these toys, Milo used to find it necessary to hide them. She would drop them, one by one, from the top of the cage to the floor. Then, she would climb down her ladder to the floor and drag or carry the toys, one by one, to her special little spot underneath a chair in our living room. It was her little "secret stash."
In his younger days, PJ had an obsession with human feet (especially feet in white socks). He would run all around the living room and inspect each pair of feet. He would sing to the feet, bow to the feet, climb on the feet and pound the big toe with his head repeatedly. His favoite pair of feet are my mom's, in white slippers. This is often where he chooses to sit, even in his older years.
Kiwi loves to see me exercise, and gets very excited when I dance or do stretches or pilates on the living room floor. She comes over to inspect what I am doing, and climbs up onto my stomach. (This makes it very difficult to continue my exercise routine, but I don't have the heart to move her, so I just let her sit there and chill on my stomach.)
Scout sings beautifully, but only when he's left alone. If you bring another bird near, especially one of the other cockatiels, he will begin to sing loudly and his singing turns into more of an alarm sound.
It's fun to take the birds to another room, and inevitably, you'll start to hear Scout singing quietly to himself in the other room. Practicing?
Pixel used to tuck herself in her cage when she wanted to go to sleep and she would start chattering loudly. This continued until the lights and music or TV went off, and the humans went to bed. She was pretty particular about her bed time.
Scout's alarm squawk also sounds at about 8:00 AM on the weekend (we never sleep that late during the week). He can be off by 15 minutes here or there, but he's pretty consistent. We never have been able to break him of that habit...