What a great question.
My big white sweet and loving bunny Jack is really a very emotionally expressive bunny. (though my other two, of course, also have emotions, they just express it through more subtle body language)
I first met Jack at Animal Care and Control when I was taking pictures of their rabbits for the local House Rabbit Society. Jack would lunge,huff and growl, but then afterward he'd get this adorable expression on his face with his brows turned down in a sad scared look (yes, the top of his eyes, his brow bone area, turns down when he's scared or upset.) I've never seen it so obvious on any bunny before. It almost looks like how dogs express sadness.
Anyway, I felt for him so much, and I reached in to take him out of his pen so I could get a better picture, and he just settled right down and became a sweet gentle bunny.
I ended up fostering him. (later adopting him)
I put him in the bathroom the first night where I knew it would be quiet and he would be away from my other bunnies. I told my husband to offer Jack a treat each time he put his hand down to pet Jack, but that Jack would first growl very loud, but I told my husband not to worry because Jack wouldn't bite,
Well, the next morning, I heard my husband yell something about "Crazy Bunny"as he raced out of the bathroom.
"Uh, Oh!" I said, "Did he bite you?"
My husband said, "No, but did you hear that growl?!!, He sounds like a dog, and he flew out at me. He scared the $#%! out of me!"
Anyway, Jack never did bite us, EVER, and so we learned to close our eyes when we reached out to him with a treat, and then we'd pet him - he loved affection once he realized that was another thing hands were good for. And soon he stopped lunging and growling.
Now he does binkies everyday before he gets fed, and when his girl Rucy has left his side and comes back,and just because he's happy to be out and about! (That's why I can get pictures of him binkying - I have so many chances)
If he's upset about being shooed from a naughty chewing spot he'll huff and growl, unless he's feeling playful, then he'll just do another binky on his way out.
When he wants affection, he'll come over and nose us, or stand nearby in a "chocolate bunny" stance and eye us. Then if he even thinks we're going to pet him, his brow goes up, his eyes get wide, and he pushes he head quickly toward our hands, and then as soon as our fingers touch his head, he presses his chin to the ground, still with his eyes wide - looking excited to be pet, then when he realizes we're there for more than a passing scratch, he closes his eyes completely with relaxation.
If he thinks we're making too much noise putting the dishes away, he'll hide in his house, but poke his head out with that "sad puppy" face, and we know we need to be more quiet for his sensitive ears.
I could go on and on about what an expressive personality he has. He is so easy to read with that flexible brow of his! He's such a fun bunny to be around, I can't believe anyone ever gave away such a gem. But we are so blessed to have him. He can really make a the roughest of days better - I know that's sooo sappy, but it's true.