[icebraining]

You're confusing resource with representation. An URL is a resource, but if the representation of that is a JSON document or a picture of him/her, that's up to the server. Just because an header affects the representation of a resource, doesn't mean they're different resources.

[rubyrescue]

actually that's a good example that makes my point. if i said to you - well if you want to retrieve a person's user information, just GET /users/1 with Accept: text/json. If you want their photo, just GET /users/1 with Accept: image/jpeg - philosophically, i'm not violating the 'rules of REST' but it feels wrong to me.

[icebraining]

Sure, I would create a "User's photo" resource too and link it from /users/1, but that's because a user's photo can be a new resource, so it can have its own URL.