When it comes to photos you just cannot beat Flickr, and you will find them used by most major websites that love web 2.0.
On Flickr you can see a cool interactive photo of a cluttered desk which represents just a small set of the many powerful ways you can use flickr.
You can use the notes within the image which when you hover over them give you extra information and will take you to an area explaining more.
Cool photo site Flickr