Photo hosting does reduce the load on the Cellar. It also allows larger pictures, which may slow down page loading for dial-up. It also allows more than two pictures per post.
I use flickr, but there are plenty of others. With flickr, you have to keep in mind that their terms of service require that the picture link back to its flickr page, so you click
, paste the image URL, then select the picture and click
, and paste in the flickr image page URL.