this add on for Firefox is really cool, I used to have to do a complete screen capture, then copy paste to paint, crop it, and then host it on imageshack or any other...
quite a pain in the neck and it also meant that a lot of funny material was not shown because it was too much work just for some stupid
But no more!
Find the add on here:https://addons.mozilla.org/en-US/firefox/addon/9924/
It is pretty straight forward to use, you can edit the pic in an online app, save it to your desktop or directly host it to post it on your favourite forum