Izzy is one. She's not loud, but boy does she like to let you know she's around. Mews from dawn to dusk, mixing a full on 'meow I don't know what I want but I want you to know it' with random trills. One of her most amazing skills is being a guard cat! If someone comes to the front door and I'm upstairs, she shoots up and meows at me to let me know.
She also meows in her sleep. Cat dreams, chasing birds or whatever she's thinking about, while emitting little murrs and eeps. It's funny to lie there and watch her trill.
Iz was sat staring out of the window at a bird, which there are a lot of round here. Then she started clicking her teeth and letting out a series of high pitched squeaks. "Come play with me birdie, I want to be your friend!" or something.
She's curled up on the chair next to me as I type. Letting out little low-pitched mrrrs. What is going on in there Iz?
A friend visiting the other day watched her for a while and said "I've never seen such a talkative moggie." How chatty is your cat?