LOL.
WE LUBS PICTURES!!
Do you mean like IMage Shack, Photobucket etc? Of course you can! Even if you have your own domain/server you can use that.
The only restriction is bandwidth leeching or hotlinking where one links to pictures hosted somewhere else without permission etc. For instance if I threw ]img[ tags around the URL for a pic hosted on Kingsnake or something.
I know that's not what you meant and you wouldnt do that - but figured it beared mentioning while on the subject (generally we don't encounter folks trying to do this much).
We hope one day to be able to offer folks more gallery space - it's difficult trying to pare down and delete images!