Yea' Lee sin is one of the best examples, Q, Q to your enemy second you hit w back to a minion ward and get away. Same with Renekton jumping over minions to get a champ. There has been so many times in recent games where I have though if I didn't have smart cast on I could have died, it really makes all the difference. Yesterday I was making big plays on a very very very quick acting Vayne, I was BC and due to smart cast you can really think on your feet and react based on the situation, got our AD ahead so much and really shut down their Vayne due to it. Brand is also another amazing smart cast champ.
Not sure how many of you do but don't play with fixed camera either.