I use imjur http://imgur.com/?noFlash
I haven't bothered to set up an account, you just go there an upload your pic, you loose control of it but that isn't an issue for me. I do have a word doc with the links for pics I might want to use again. It allows png files which like gifs can have transparent backgrounds. I've noticed some of the non genuine spoons are jpg with a white background.
Seeing as though this is a tutorial some image format basics.
jpg, good for photos, compressed for smaller file size, some loss of quality (lossy) but probably insignificant.
gif limited to 256 colours, not suitable for photos, can be animated and have transparent background.
PNG is like an improved gif which allows for greater colour depth, not really for photos unless small otherwise results in large file size.