Furthermore to comics and image series: an animation.
This one is full on M/M penis/macro growth. Its very silly.
http://www.furaffinity.net/view/29999325/
Need log-on for the one above. Once again, if you browse my favourites/uploads on there you will find more penis expansion themed things.
I would love to commission a female growth animation sometime but there are very few animators with suitable models. I'm not overly fond of human models for some reason, plus its all fantasy so I prefer furry themed things for growth.