Never heard of Pbase, but I'll have to check that out. I normally use Photobucket...
There's a small cost to using it - I pay about £12 a year for over 8000 pics stored.
TOS is good also:
http://www.pbase.com/tos
Any images uploaded by a user remain the property of that user or whatever party holds the copyright.
By uploading images, a user does not surrender his/her copyright or ownership of the images.
I found the bit on Flickr
by using Flickr you are letting them have rolayty free use of your photo's. It's part of their T&C's
(b) With respect to Content you elect to post for inclusion in publicly accessible areas of Yahoo! Groups or that consists of photos or other graphics you elect to post to any other publicly accessible area of the Service, you grant Yahoo! a world-wide, royalty free and non-exclusive licence to reproduce, modify, adapt and publish such Content on the Service solely for the purpose of displaying, distributing and promoting the specific Yahoo! Group to which such Content was submitted, or, in the case of photos or graphics, solely for the purpose for which such photo or graphic was submitted to the Service. This licence exists only for as long as you elect to continue to include such Content on the Service and shall be terminated at the time you delete such Content from the Service.
(c) With respect to all other Content you elect to post to other publicly accessible areas of the Service, you grant Yahoo! the royalty-free, perpetual, irrevocable, non-exclusive and fully sub-licensable right and licence to use, reproduce, modify, adapt, publish, translate, create derivative works from, distribute, perform and display such Content (in whole or part) worldwide and/or to incorporate it in other works in any form, media, or technology now known or later developed.