Great site, with a well thought out presentation.
Some of the things that came to mind though:
The "random photo" which represents the user that uploads the pictures to you is your business card, let it stand out more.
The banner looks great, however the dominant white space below overshadows the pictures. Either color the backdrop or make the pictures larger. You have too much to show off to let the white take over "the show".
All things considered, you have incredible images posted, yet users can only vote on them. Think about the story behind the image, why was it taken, why does a viewer vote for it, what are the viewers thoughts on it?; let them speak. Add a blog or something of that kind, where users can present their point of view about a picture. At the same time, the person that shot the photo has more room to leave an explanation and get the talking started.
It should get the momentum going to have a not just visually vibrant site, but also connect people.
I assume it would make sense to offer these pictures as screensavers or backgrounds, eventually add some "tag lines" and you're along the path where thousands of offices have these guidance/teambuilding/wisdom posters on the wall. It's a million dollar industry. Your images there are every bit as goodlooking, plus you have the added feature of users telling you what they like via the voting process. If you own the copy rights to the pictures, i'd consider tapping into that market.
Before i go completely off trail here, the site is well done. Add some more interactive, user driven content and you're right there with the best of them.
:tu: