PHOTO CLUB is another site worth considering:
http://www.clubphoto.com/memberservices/login.php
They have a "free basic membership":
http://www.clubphoto.com/_cgi-bin/members/sign_up.pl
You can post your pictures on the forum so others can view them without having to "sign-in"--just post the picture's "properties" (URL address) from your PHOTO CLUB Album between [img]s...
see the forum's FAQs about posting pictures/images.