Firefox Screenshots

Firefox has already features for doing that.

it has selection?

...

just for one little snipit...

...

absolutely no reason for this to exist when i have other applications that do it for me, do it better, and do it across my whole system and not just my browser

Can they print the entire webpage and/or upload the image to an image hosting service directly?

Not him but OneDrive, Dropbox, Gyazo, etc. do that, yeah.

Sites like flickr have an API with bindings for various languages, so it's easy to write CLI program, if what you need doesn't already exist.

Really stimulates the neurons.