If you are creating presentations, ever, you should always start with SlideShare. For some reason, there are people online who feel that posting and sharing their powerpoint presentation on every topic from Mobile Marketing to Dog Breeds is a good way to spend their time.
It's good for us who need the info, but what benefit do they have for posting?
Not sure, but I won't tell them if you don't.
errr... maybe I just did. Whoops. Oh well!