Well, to me, you are trying to solve the wrong problem. Everyone is voting for what they like which all goes into one big pool. I think you should let people create groups with their own rules.

Flickr already has a very active scene where people create groups that are voted on in various ways, but it's very ad-hoc. Here are a few examples of the types of groups:

Post pictures with at least 50 favs http://www.flickr.com/groups/greatpix50/

Pictures with a least 4000 views http://www.flickr.com/groups/views4000/

Post a picture of a tree, comment on one http://www.flickr.com/groups/the_tree/

Post one, award two http://www.flickr.com/groups/history-mystery/

Top 20 Travel Pics http://www.flickr.com/groups/top20travelpix/

I would suggest looking at what these people are doing and seeing if you can make a better system for them.