My cat used to by my in-laws' cat. They moved out of state and didn't want to drag him across the country, so now he's ours. He's been with us for over ten years, so it seems like he was always our kitty. My mother-in-law actually adopted him from a Burger King parking lot! She saw a kitten running around and gave him a piece of sausage, and then he jumped in her car when she got in.
My cockatiel came from a pet store, but he's a rescue (the owners of that particular store are involved in bird rescue, and almost always have rescues up for adoption). I went to check out the birds, saw the little bald one, and just fell in love. I asked to see him, and he immediately ran up to my shoulder and started preening my hair. Yeah, he went home with me about a half hour later.