I recommend Snapfish or Yorkphoto.... (they use the same nice interface)
I get Snapfish free with my cable ISP, but you might be able to get it free too, I don't know what their usual is. But before that, I used York, and you can have it free for a year, if you buy prints or something from them, you can have it another year.
They will only post pics to a max size of about 400x600, but sometimes that is a good thing, and the links are really stable. (really LONG URLs, but stable.)
http://www.snapfish.com http://www.yorkphoto.com