Just a FYI, I've got someone building a photo comp tool for me that will hopefully streamline things with the photo comps that we run. Some of the features I've asked for:
User submissions - you submit your own entries
All entries are anonymous until winner chosen - makes for an unbiased comp
Vote on up to 3 elements on each pic (e.g. quality, originality, etc...) - helps to level the playing field with expert and novice photographers
Not all comps will be like this though, some will still be voting for the best
Sidebar widget to show running comps etc...