Walmart Photolab
Personally I alternate between two services; Flickr and Photobucket. www.flickr.com www.photobucket.com
i like to use flickr as well.
Personally, I prefer smugmug. It isn’t free like the other ones listed above, but, you really do get what you pay for…
Oops on the link. That should be www.smugmug.com
smugmug pretty much rocks the casbah.