How to make convex/concave picture on photography?

Photos like this:

I have an iphone, Macbook pro and Nikon D40. All help in need!

You need a fisheye lens. You can also play around in photoshop and distort an image to look like that.

A Fish eye Lense…

They Have fish eye as a setting in Photo Booth on a Mac Book pro.

For your camera there's this http://www.amazon.com/...B000ZPJEDE

If you want to edit that to look like that you may wanna use photoshop.
Or any photo editing software like that ^.^

It's actually an undesirable effect in my opinion. Though inevitable with wide fisheye lenses.