Save Toby from a few years back where the author posted several pictures of a cute bunny and said that he was broke and out of money. As a result he would have to eat his beloved rabbit if he didn't raise enough money to pay his bills. The donations started pouring in (along with the controversy à la organizations like PETA). The thing about the Save Toby campaign is that no matter how you viewed the website, it was engaging on an emotional level. I saw it as a great joke (humor), some people saw it as a tragedy and gave money (sympathy, pity), others saw it as a travesty and fought to shut down the site (anger).
One of the ways that ideas are sticky, according to Made to Stick: Why Some Ideas Survive and Others Die, is that they provide an emotional connection. In one sense it doesn't matter much what emotion you use. They all connect people with an idea and get them moving toward action. But emotions will only carry an idea so far. After that something else needs to kick in and get people moving (joy, community, reward, purpose, etc.).
I don't know if you had a similar experience in youth group, but when I was going through there was a strong emphasis on emotional connection. We would spend time thinking about how our sins made Jesus suffer on the cross and even go so far as to nail a piece of paper with our sin written on it to a cross. There were a lot of emotions involved, but the change wasn't lasting because the emotions were mostly negative (guilt, fear, shame) and didn't connect to any positive way to change.
This isn't too far off of the hell-fire and brimstone sermons of a past age. The thought is that if you scare people or make them feel guilty, then they'll do what's right. That might be true, for the short term, but in the long run it won't be a lasting change.
A good presenter uses emotions to connect with people, but uses them wisely.
How do you provide an emotional connection when you speak?
(Note: the book link earns me a small commission on any sales.)