Nothing like real-world application of calculations to light the fire in the belly for the love of math. Irony is that it's not even magic at all laying all these numbers and dissecting what they mean in a systematic way. If there is magic, it is in the insight!
Found a great resource for that by the name of Steven Strogatz.
Check out his post on conditional probability. Chances are you'll never think of abstract percentages the same way again.