If you use Firefox there is a nice PlugIn for it to host your images comfortably, using integrates Imgur, Photobucket, and ImageShack:
https://addons.mozilla.org/de/firefox/addon/1174/ Once you installed it just click the right mouse button on the image you want to use and chose "Upload image" - thats it (at least, as long as the picture is online somewhere already - otherwise you have to open it in a browser window first).
