Let a user change picture from their system files

I have a material, and whatever i change the picture to works fine, but what i want to do is i want the user to choose any picture form their system files. So basically, i want the user to be able to pick a picture in game, i also want the material to stay the same if i do Application.LoadLevel(0), but that probably wont be an issue. So how would i go about doing this? Like on the iphone it would take you to camera roll, on the android it takes you to pictures, and on a computer it takes you to system files. Is there an easy already pre-implemented thing i can use to do this?

As far as I’m aware at runtime there’s no way to pop open a file browser. I’ve resorted to using the following solution in the past: