Over the past few years I have been teaching exponential an logarithmic functions as part of my course load. A student teacher I was working with found this great website which explains many Math topics in easy to grasp visual and contextual ways. I really like the authors explanation on compound and continuous interest as it leads to the famous (1+1/x)^x formula. I use this explanation with a little hands on activity in the classroom and it really helps.
The website is betterexplained.com