There are various servers out there that do free hostings, either they require your viewers to register or give bad compressions of your picts, only allow for thumbnails or aren't very user friendly or blah blah blah.
Sometimes its wise to pay a minimal sum to have a fast and reliable server to do the job.......
Anyway, if the little things don't matter so much, there are tonnes of hosts out there, just do a search.
I'm using sony's image station (www.imagestation.com)
-the layout's a little odd (hard to navigate)
-they provide quite good compression and original sized picts posting
-a little slow due to traffic
-Good uploading tool
-limited album capabilities
-friends who visit have to register (free) to use some features