Photobucket.com would be my first suggestion for anyone looking for free image hosting. They'll crop down overly large images, but you have a pretty big amount of hosting, last I checked it was still free and your account and survive a decent amount of bandwidth per month.
If the cropping is too draconian, I imagine that one could split one's image into several, perhaps quartering or halving it, and posting them side-by-side or in a square.
EDIT: I imagined that anyone with free hosting suggestions could post them here.