Have a look at this recent review of 10 online photo-sharing sites click here.
I've used a few of the above in the past, & still a member of Kodak Easyshare Gallery (on the 2nd page of above link), though I've only ever viewed others (my brother's) albums - not uploaded any of my own yet. For many of the above, I think both (the poster & viewer) need to be registered members.
For hosting a few quick pics (no membership required by either party), I've used Imageshack click here & Tinypic click here.
Then there's Webshots Desktop click here (who also have their own free software click here). It's quite popular with some folk - 37 million downloads from one site itself click here. G