I love this service, and I think you've done a great job with it! Finally I have found a better place for my pictures than Flickr!
But there is one thing that is bothering me; Why do you demand that people log in before they can see the original sized version of my creative commons licensed photos, and why do I have to be a pro to see the original sized version of non-CCed photos?
It is not your pictures to do what you want with, and when I spend so much of my monthly bandwidth uploading the original sized version of the photos, I do that because I want people to be able to see and enjoy them, not to make you money. Especially when I license them under a Creative Commons license, you should not make the choice for me of who should, and who should not, be able to see the largest size of my photos.
I am thinking about becoming a pro member myself, because I really, really like this place, and I think you've done a lot of things right, but I'm not quite there yet, and this is one of the things that makes me think twice about it.
Until you change this practice I will add a link to the original size in the comment field of all my photos.
I know that you provide this excellent service free of charge, and fully understand that you need to make money somehow, but this is not the way to go about it!